My advice would be to try to specialize in a channel. I think social or video have the most upside, and are what I’d learn if I was starting today. I specialized in paid search starting about 10 years ago. I now have a big advantage over someone in the first year of 5 of their career when it comes to paid search, which makes it easier for me to get new clients who spend significant amounts of money on google ads than it is for less experienced/proficient people.
Now I’m focusing on other parts of my skill stack like networking and people management. It only takes a small amount of effort for me to maintain my advantage in paid search. If you try to be the best at everything digital, I can’t imagine a way you’ll achieve that. If you aim to be really good at one thing, your odds are much better.