Can you get back your hard earned ELO points once you lost against a cheater, and they got banned?

He had maximum accuracy, so I reported him and he got banned.

I think that you should be able to get your points back, if they are proven to be cheating in your game against them.

High accuracy is not an indication of cheating: Chess.com uses much more sophisticated and accurate ways to identify cheaters, none of which can be discussed in the public forums.

You do get your rating points back for any games you lost against a banned opponent: you did not lose your game against them (which is a pretty good indication they weren't cheting against you in that partoicular game) and it's really just a placebo anyway, since after you play a few more games its effect on your overall rating will have been washed out.

I get refund points

You might want to mask that profanity better - it got past the mods the first time.

Also, you have to understand the nature of your rating: it's your relative position in the pool of players at that particular time control. It's not like there's only a fixed number of ratings points that you forever lose out on: after 50 games, your rating will have returned to its normal level. Heck, after getting the ratings points refunded from a cheating opponent, that also gets washed out after more games so that you come back down to where you should be. It's absolutely just to make people feel better about their rating because they don't understand what the rating actually represents.