The biggest problem is that you can't sit out losses in a situation like this because you are dependent on the money.
You only need to look at the Bitcoin market. For example, if you invested 60k in BTC at the end of the last bull run, you now have a (very large) loss for 2 years. If you are dependent on the money during this time, you will have to sell the BTCs again at a significant loss.
However, if you invest money that you don't actually need, you can skip the 2 years and wait until the prices improve again ... and even if you start with 60k, you are currently making a positive exit.
Patience and time is everything ...
That is of course a possibility, but "money you do not need" is not something we can be sure about. Like for example last time I invested heavily, I did that with money I did not need, but then something changed in life and I needed that money and I had to cash it out, wasn't my ideal situation, wasn't what I wanted, but I had literally no other option at all.
In the end, it didn't help anything, and we just did it for a bit more ease of our mind, but I had to do it. So, not everyone can know if you will need that money or not, you may think that you won't, but life could throw you a curveball and suddenly you will need it. Being a crypto trader, one should never rely on trading profits because it is pure uncertain stream of income. So, OP is right here but for my case I am not a crypto trader and I am not living out of trading anyhow.