In the history of markets, there has never been a major uptrend that has not ended badly. That is the nature of markets. But whenever stocks are running hot, there is always a stock market pundit that is anxious to point that it won't last. It is never different. As long as there are markets, they will go through cycles of ups and downs.
The compulsion to say things like, "this will end badly" is primarily driven by trying to find a justification for why someone is not participating in a strong market: "I may not be making money right now, but that is OK, because this will end badly."
By stating this like it is some astute observation, it makes the poor timing a bit more palatable.
My job as a trader isn't to find emotional justifications for my actions, but to try to produce the highest level of profit I possibly can. Profits and losses are the only scorecard that matters when you are a trader. Predicting that the trend won't last forever doesn't help to put points on the board.
If someone wants to offer helpful advice, don't point out the cyclical nature of the market. Tell us how to extract as much profit as we can during a downtrend and how to exit quickly at the first sign of weakness. That is what counts the most. We don't need more empty platitudes about the nature of the market movement.
Yes, this is going to end badly. Yes, we will eventually suffer through an ugly bear market. But right now the focus should be on trying to navigate positive action while it lasts. It may end soon and it is not an easy task to trade powerful momentum in a strong market.
My advice is to keep pushing, stay vigilant, and focus on the price action. While that is vague advice, it is much more useful than "this will end badly."