It's so extremely volatile and unpredictable.
Imo no sensible person could call it an investment these days, it's speculation at best, or just plain gambling at worst.
Literally though dumb luck I turned £250 into £3500 in 2 years in the early 2010s. I needed the money so badly by that point, and cashed it in, but if I'd had a crystal ball, I'd have waited for the much higher peak a couple of years later, by which point I could have netted £150,000.
It seems to me that it won't ever be possible again to turn £250 into £150,000 in the space of roughly 5 years. The huge rises have already happened, and it's unlikely that the trajectory will rise that dramatically ever again imo (based on nothing more than a little experience, studying the charts and timelines, and listening to people that seem to know what they are talking about.)
It's more likely that £150,000 will turn into £250.
But obviously no one really knows what the future is for the valuation of BTC.