and most people who hold bitcoin will definitely sell their bitcoin when bitcoin has reached a high price of $ 25k. and of course if many sell then this will make the price of bitcoin go down again.
It really depends. Smart money definitely has exits strategies, but most people (dumb money) act irrationally during either bear or bull markets.
I have seen it happen around me where people aren't satisfied with the number of coins that they hold and think it's better to add to their position instead of unloading. I think it's safe to say that we all have gone through a time where we wish we bought more coins instead of being so conservative. It's tough to see the price go up a lot while at the same time thinking about how much profit you could have had if you bought more.
In the end, it's better to just have a big fat hodl stack and sit on it for 5-10 years than to worry about missing out on the next bull cycle. The base floor of the price keeps increasing steadily, but gets a massive boost after each bull cycle, even after the 70-80% bear market.