It is possible that Bitcoin price reach $250k, but it will soon after that drop under $100k. Also I would speculate that more possible time frame is 24 months and not 12-18.
The same pattern as it did with its past all time highs. $250k is such a huge amount to think of and IIRC, there's one famous crypto guy that has predicted this, Tim Draper.
(
https://cointelegraph.com/news/tim-draper-doubles-down-on-his-250k-btc-prediction)
2017 Bullrun had made this person become famous as he perfectly projected it but I don't think he gonna be right again this time. $250k is really high and never in mind to think we can reach it, maybe $50k is close to reality than this. However, it was him to project and give his optimistic speculation (and I believe we all that the same) and it's up to us to draw any conclusions as anyone can make their opinion as well. But just to say that it looks impossible and never have to expect for it.
He might able to project that previous ATH but doesnt mean that he do able to predict prices in the future and i do agree on what you have said that he might able to guess that one but
250k number wont really be an easy one to achieve on the current value we are standing into.
Lots of speculations floating around like 50k-100k-250k or even millions and i dont know on where they do get these numbers.Being optimistic isnt really bad but at least we should
try to look back if those are realistic or achievable.