I'd be broke
no doubt

no one knows about the internet in the 20's
so my programming skills wouldn't get me very far

I haven't read enough about historic sporting events
to make any money gambling

I wouldn't even know how to apply for a job
would I have to use a typewriter to type my resume?

I could start a moonshining business
but I wouldn't know where to get the moonshine

I could predict the future for a fee
but I would be limited to things that happen in the distant future

perhaps I could write a fictional novel of a dystopian future
and just write my memoir of everything I can remember