Does it even make sense to put money in a savings account vs it in a highly liquid investment. I always hear to limit exposure but at the same time, "Investments always go up long run"?

I am perplexed. I always here people saying to not put more than 50% of cash into investments or some conservative figure. At the same time, I lowkey get messages that investments will only go up.

I am asking this because at the moment, I have like 40% of my cash in savings account and I find it a waste while I watch my investment grow. Same time, articles are always saying investments will always go up long run, passive investing, etc etc

Should I just take this as "diversification",