How to deal with tilt?

I'll try to post a longer answer later.

Please do. I know, it's really hard to put a few words into a sentence when you're tilting about chess, but I believe in you. You can do it! More importantly, believe in yourself!

Understanding the concept of tilt would help. There's no tilt in chess.
first of all, yes, there is, as i'd like to elaborate below.

Tilt makes sense in games like poker, where you can be playing a 100% correct game (given the information you have at the time), but still lose hand after hand after hand due to the natural variance of the game. This makes you doubt yourself, messes with your mind and makes you play a losing game. You play more & more to overcome the perceived variance, but since you're now playing a losing game, you lose even more. This can be extremely difficult to handle psychologically, and it ruins you.
Chess is a game of perfect information, but it absolutely is prone to variance and external factors as well. Things like one's mood, level of external distraction, energy, psychological factors, all affect one's play. Plus, if you somehow saw the same position 10 times without remembering each time, wouldn't you think you may not see the same things in the position each time? Some concepts you may have solid, some may be hit-or-miss. So yes, variance is a thing. One interesting point is that, external analysis has shown that Hikaru plays the lowest quality chess against Magnus. Why? Because of the intimidation factor....makes it harder to concentrate well and see only what information the board gives.

In chess, if you play a 100% game, you don't lose. So if your rating is going down, that's because you're not playing as well as you might think. This is factually true, and sometimes relevant, but not always. Again, there are factors that cause you to play less well that are not pure chess skill. You should spend more time working on improving your game. There's no variance element in chess, so no easy excuses for poor decisions, other than lack of skill. Again, blatantly false. This is like saying the only reason I can score poorly on a test is that I didn't study hard enough -- things like sleep, nutrition, personal factors, overall stress management etc. don't matter at all. Therefore tilt, in its pure form, shouldn't happen, as you only ever have yourself to blame. I don't know what the pure form of tilt is, but this is a very unhelpful sentiment. One of the biggest driving forces of tilt for many people is frustration and self-doubt, which impact concentration and together can make for long bad streaks. This is something I want to point out because I sincerely feel this idea can be harmful for many people. Encouraging people to blame themselves can actually just make the situation worse.

There can be cases where you are playing very tired, in which case your game might be a lot lower than your natural level, but at 800-900 that shouldn't matter too much: understanding the most basic chess concepts + a little experience should get you to at least 1200 anyway.At all levels above sheer beginner level I'd say it's important to learn and improve on all aspects of the game. As someone higher rated than you, I think I can say that you're deceiving yourself if you say that players of your level or mine have definitely got all the basics down solid. I know opening principles, but that doesn't mean I execute them perfectly. Unfortunately, people oversimplify the learning process and give the misleading sense that it should be "easy" for everyone to progress to a certain level (that is somewhat below theirs). I remember what 800-900 was like, and I don't think it is true or helpful to say to someone at that level that external circumstances don't matter much because their games are simple. That isn't true. A 2000 could say that about you or me; how'd you feel about that?

Okay, let me actually respond to the OP.
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Just as a brief sidenote, daily games I wouldn't say don't help improve. Granted I don't play it much nowadays, but I know what it's like. The thing with blitz and bullet is you don't have enough time to go through a thorough thought process and that's not the case for daily.
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First of all, nice peak rating! It's always nice when that happens. However, I think a little bit of perspective may help. Losing 30 points in one day is very normal. In fact, in the long run it's normal to have a lot of dips; chess progress isn't linear and your rating will vary naturally. You can't expect to be at your peak rating all the time; you would in general spend a lot of your time below your peak. As you improve in chess overall though, your rating should go up overall, and the small fluctuations won't hold that much importance in the bigger picture. So imo, you shouldn't stress over 30 rating points. On my 2nd my rapid is about 30 points lower than my rating ~20 games ago as well, but to me that's quite natural due to variance.
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Hope that helps at least a little bit. Some days you'll win a lot, some days you'll lose a lot. As other posters have pointed out, if you play more games it's likely you'll win a bunch of games at some point....30 points is really not a huge loss.
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An addendum: Like I said previously, external factors matter....and when I'm aware of it, I'm careful to not consider it a reflection of my ability because as I said before, frustration can compound and worsen tilt. So I'd advise you to try to avoid stressing out over tilt. The other day I stayed up really late this one time and the next day I immediately threw over 200 points of blitz rating to the wind. I knew the reason why though, and as such, I didn't feel bad or feel I had worsened, and shortly after was back to my original rating and more; if I had let self-doubt get to me, I absolutely think it would be difficult to get back to 1700 in blitz, but as it is I had a 12-game winstreak on the way up

Understanding the concept of tilt would help. There's no tilt in chess.

Tilt makes sense in games like poker...

I play both chess and poker. Tilt DOES exist in chess. It is just that people can more easily go on tilt in poker because of the coolers and bad beats (in addition to higher variance due to the luck element in the short-term).

Tilt exists in chess because tilt is anything which makes you play at less than your ability and chess is played by human players (like poker) and humans have emotions. People can get angry, disappointed, or discouraged with their chess (as well as poker). These emotions can negatively impact your play in future games, so yes chess does have tilt.

I have considered making a future chess video on how to deal with tilt, but this is a complicated topic if we are to get to the root of the problem, so I don't think I'll get to that video anytime soon. In the meantime, I created a similar video just recently on how to stop losing chess rating and this is certainly connected to variance, tilt and similar factors:

Yaaay @KeSetoKaiba arrived on the scene :) Didn't know you played poker btw.