I bought some bitcoin at 26/27/30 and 31k. all profit so far, I am thinking about buying more, but is 35k te expensive to buy bitcoin?
You're in the best position to answer this yourself because it depends on how much you believe in bitcoin and it potential. one of the things to be aware of is that the crypto market is highly volatile and the price of Bitcoin can fluctuate quite a bit. I believe you are already aware that there's a risk of losing money if the price drops. But at the same time, there's also a chance of making even more profits if the price goes up. So the decision to buy Bitcoin at any given price is really up to you and your own risk tolerance.
If you believe in the long term potential of bitcoin, you can still buy now. Although, it's impossible to say for sure whether 35k is too expensive to buy Bitcoin since the price of Bitcoin is constantly changing but tracing back the history, we have a long way to go and you can make use of this opportunity. Just risk what you can afford to lose.