It’s not as if you get n shares priced at $x if you owned one share prices at $x. When a stock splits you get n shares each worth $x/n. The purpose is to lower the trading price for an individual share.

It's more like a recognition that the sales price probably has gone up a lot and that management likely has some level of confidence that it will continue to increase--though that is of course not a guarantee that NVIDIA is a good investment today.

stock splits don't change the value of your holdings