for $4000, I'd probably choose just 1 coin, which is BNB. i believe that the potential of BNB can be the same as ethereum. nowadays, you can't buy 1 ethereum for $4k, but a few years ago, it cost the same as BNB, and you could have a lot of it for $4k.
at the moment, the potential for BNB seems to be superior to that of ETH, and if my hunch is right, the price of BNB could be as high as ETH is today. for $4k, right now you can get some BNB. it's quite worth it.
Bnb is one kind of good investment and there is no doubt. But personally, I believe it's not good to invest all of your money in one coin. There is a proverb'' Don't Put All Your Eggs in One Basket ''. If something bad happens, you will be at a big loss. So it would be nice to do split the money and make investments in some other project. For a good investment, there must be a need for A great Risk management system.
$4000 is a good amount to make some investment. Personally, I suggest buying 6-8 coins with this amount. Ada, BNB, Link, Dot, Tomocahin, CRV, DIA, SXP, etc is my choice for this. Also for the long-term investment DCA system is good, in this way anyone can able to buy preferred coins at a low price.