"high" only depends on your perspective. if you think price should be $5k then yes, $10k is high. but if you think price should be $20k then $10k is a discount!
so what happens is that investors don't come in based on what the number is for the price but they only come when they speculate about what this number could be in the future. so if they see the potential and realize that price is going to reach at least $100k in the next rally phase they wouldn't hesitate investing no matter what the current price is.
the problem however is that they are not yet seeing that potential and most investors wait too long to realize it. that is why we have a lot of entry near the bubble's peak each time!