Math is pretty universal. Big data, statistics, analytics, probability, and the list goes on and on...
Although considering the current state of these jobs, while they pay big bucks and are highly sought-after, it's a really soul-crushing experience. They will milk you to exhaustion.
As for feeling useless, it takes some time to find your place. Scavange places, talk with others, etc.
I've ran out of character limit, but I should clarify that only "big tech" of the jobs I've listed are soul-crushing. Outside of it it's highly possible to go to retirement from a good and respectful workplace in the areas I have listed.
Math is pretty universal. Big data, statistics, analytics, probability, and the list goes on and on...
Although considering the current state of these jobs, while they pay big bucks and are highly sought-after, it's a really soul-crushing experience. They will milk you to exhaustion.
As for feeling useless, it takes some time to find your place. Scavange places, talk with others, etc.