Actually, diversification is a good way to minimize the risks of losing your money when the price is down. But, of course, you must be careful to choose which coins to buy after having funds later. Never buy the coins based on the hype market.
I agree with you about diversification, it is important so that a falling investment is cushioned by other investments.
Unfortunately, this only works to a very limited extent with cryptos. BTC drives the market, if it falls, the altcoins fall as well. As an investor, I must therefore see my entire crypto portfolio as a unit and must not forget or forego other diversifications (real estate, stocks, ...) - stablecoins of course left out.