The overbought level on the RSI does not necessarily means that a crash is near, we must remember that markets can be irrational and if there is a lot of hype around that coin then the RSI could remain in those levels for months, personally if I were you I would not invest as the chances we are seeing yet another manipulation event by some whales is very high and I do not want to buy a coin that has so weak fundamentals for such a high price, because if the crash does indeed comes and you do not sell fast enough then you could need to hold your coins for years.
The problem with chart reading is the fact that it shows people what it should do but people sometimes do not care. I believe that chart is something that should not be the reason we make our decisions if we are dealing in crypto, it could be something that would be okay if we are in stock market but not when we are in crypto world because we are way too emotional to care about the charts. Of course, it will happen sometimes, but not every single time and that is why you should not be making any trades based on the charts basically.
There are situations in the crypto world where it looks like it is going to go up but then it goes down that is not because chart was wrong, chart did show what it should show, but chart is a chart and not human and doesn't have money so it doesn't buy or sell, it is humans that buy and sell which means while chart shows it is going up, people could still sell while ignoring the charts. Reverse is possible like you said as well.
We must remember the best indicator we have available is the price, I often see traders which have a soup of indicators not realizing they are obscuring the most important source of information which is the price, this is why our indicators could tell us something but the price then begins to do exactly the opposite of what we thought the price should do, and this is because as you state people can be irrational and as such markets are irrational as well, so this should be taken into account in any trading strategy.