The rule has always been simple, be it cryptos, stock, gambling and with any investment that comes with uncertainty as the case has always been with investments. You always test it out with what you can afford to loose and you continually add to it.

Cryptos has a high level of uncertainty. Most of us have grown accustomed to bitcoin and maybe the top coins with a high market capitalization to be safe for long term but that too has never been an assurance as a long term investment.
If I were to advice you on a coin to chose for an investment, it definitely would be bitcoin but on that too, you mustn't go all in as per investing more than you can afford to lose.