Sublime is closed source. When it croaks up and dies, all the skills you've built up will be wasted, and you'll have to rebuild them elsewhere.
Why not invest in something open instead? There's more options than ever before, and they're all good.
For me, VS Code seems to provide pretty decent Python IDE capabilities almost out of the box.
For those a little more deeply invested, Emacs with elpy and realgud gives me all I need: code-completion, docs, debugging, breakpoints, etc. And it's something I as a programmer can adapt to my needs and build on.
Sublime? None of that. So what's the appeal?