There just are not enough sellers left to push the market down in any meaningful way.
There is always lots of sellers available to sell and push the price down, that is the weak hands. But the important thing is that there is also a lot of buyers who would buy their coins cheap and won't let the price fall down any lower than certain levels.
For example recent weeks showed how there are still a lot of weak hands who panic sell (ie. from $40k+ down to $28k) and also there are a huge number of buyers who would be more than happy to buy bitcoin at a discount (ie. from $28k back to $34k).
Those weak hands were always here, we are talking about people who helped the 2018 bear period as well, there is no way you could stop those weak hands. However what you can do is get a lot more richer and diamond hand people involved as well, if you do that it would help to increase the price. For example, those huge corporations buying thousands of bitcoins are sort of part of this, they are basically doing what we are talking about, they buy and they hold and they do this for thousands of bitcoins.
So, basically we are on the right path, we are doing a lot better, sure we still have those weak hands we had in 2018 but this time around we have super rich people buying and holding, would it be a huge crash if those people end up selling? Yes but it would be even better afterwards for the purge, until something like that happens we are doing a lot better nowadays.
You are confusing a couple of things here.
What we had in 2018 was a bubble burst and then a bear market. It had nothing to do with weak hands. Just like bull trend, a bear trend is also a natural trend that any healthy market can enter and bitcoin had it during 2018. With or without weak hands the bear market and bubble bursts happen because they are inevitable.
Weak hands are only causing nuisance in short term. For example even today when a very simple correction starts after going over $40k we see the panic sellers (aka weak hands) dump in a frenzy and increase the size of that correction to as big as 30%.
Again when price goes up and breaks some resistance, the same people this time called panic buyers (aka weak hands) start FOMO buying bitcoin and make the rise jump up instead of slowly getting to a higher price.