1) The approval of various ETFs (so demand is heightened). It's much easier to invest in it than in was in the past.
2) Traders expecting the supply to tighten (see bitcoin halving which is due very soon) and the demand there also heightening due to supply constraint expectation.
3) A lot of the uncertainty in terms of exchanges is gone. Coinbase looks like it can stand up to scrutiny and this furthermore boosts demand.
When you have huge demand vs. constrained supply, bubbles form. Of course, are all of the factors I mentioned enough to keep the bubble going for a very long time? Well, that I can't answer. No one knows how long this will last. I can tell you though that this to me looks like it is the next Tulip bubble. I see almost no reason to use bitcoin as a store of wealth. As a decentralized currency it has tremendous value, but treating it as gold I have reservations on since a lot of corrupt gangs and regimes are currently using it as a method of payment and laundering (including North Korea), as well as it being a huge drain on the world's energy supply due to mining energy needs...I don't really see what value it brings to the world at all, so treating it as 'virtual gold' (the way the world has been treating it) makes 0 sense to me, but in general, the world in the short-term sometimes makes very little sense. Over the long term, things tend to clear up. Hopefully that helps.