The way I see it, your strategy only works in bull markets as long as what you are buying is appreciating in value. Otherwise if it is on a bear market and we have one of those long dumping years, then loss is what you'd face.
Although I have to say it also depends on your exit strategy. You said in OP that you "find exit point and sell", that can potentially help if done right. So as I said, if your strategy works, stick to it.
I can confirm. As a victim of believing my own genius in 2017
Me and 100s of others were all posting silly wins for 'potential' alts. You name it what there was then, PoS coins which not only gained in price but grew in your wallet. New Smart Contracts like WAVES (yes, and worse).
The proof was also all those companies that were reporting huge profits after 2017 they all went into loss. Then in 2021 onwards many went bankrupt.
Altcoins doesn't compare to BTC. They need to be exited, and they never recover in the next bullrun