Hi guys! So, yeah, as you must know already, all crypto has a finite supply
False statement. There are cryptos that haven't got a finite total supply. Examples of such coins are ethereum, Waves. You can check the coinmarketcap for that info.
what actually happens when bitcoin hits 21 million max besides it not being mineable anymore? Does this increase the value quicker?
Truth is that the 21million supply can never be achieved. Already, there are some bitcoin lost and can't he retrieved as a result of lost of PKeys, death, malwares etc. But once the peak (no matter what number is reached) in supply is achieved, investors will begin looking for other crypto options. I really don't see getting to the highest supply being a problem for anyone.