Bitcoin in itself is quite useful, it’s something people will exchange for usd or things of value which the gov can’t censor or directly police.
Bitcoin’s price is determined by zero fundamentals, so it will swing wildly if you zoom Out enough, forever. That’s why if you ask me it makes logical sense to have 1-10% Of the portfolio betting long or short, because it has a much better than 1 in 10 chances of going x10 or -90% in relatively short timeframe. I didn’t backtest it but looking at a chart it looks like there are those many-sigma shifts every 2 years.
To that extent, if you’re interested in betting on it, you might want to use option contracts and make sure your max loss is fixed at the premium and the upside is unlimited.