FWIW, I have recently purchased a small amount of BTC. I did this because my thesis is that a) it's been around long enough now and up and down enough in that time that it's no longer exhibiting what I would consider bubble behaviour, and b) the fundamentals about it that people believe in is that it will be a (portable) store of value that will not erode over time due to inflation once it tops out at 21m coins. In the context of my overall portfolio, I'm no longer willing to miss out on the potential upside over a ~20-year timeframe (I've dismissed it enough over the years!) compared to the downside potential, which I no longer believe will go to zero.
In short, it's either a moonshot 10-100x or a ~50% loss for me, with probably very little chance of a more benign, non-roller-coaster scenario in between - hence the very small allocation (or bet, if you prefer!).