IBD returning to work after career break possible?

Hypothetical topic (not my situation but just want to get peoples views):

I'm an investment banking associate, I made a good amount of money and say f**k it I'm quitting my job to go travelling, I get carried away and spend 2 years in Australia living on a beach, chilling and smoking weed. I've become a pot head and the only words I now know are "suh dude" (it means what's up dude - reference below). I've lost all my skills apart from rolling a blunt and now have the brain of an 18 year old pot head that has the IQ of a squirrel, if you ask me what an investment banker does I reply "erm invest?"

You've forgotten what accounting and modelling is, you've forgotten what an IM is and literally everything there is to banking. To relearn everything to the level that is expected of an associate, you would need to do the full 2-3 years of being an analyst again.

You realise what you've become and it's time to get your investment banking career back or explore other high paid careers so you quit the drugs and leave the chill life behind you flying back to the main finance hubs NYC and London.

1) You don't want to have to start your career again from the analyst level and beginning, could you make it back into an investment banking associate role or other high paid finance role like PE, given the situation above?

2) If you think this is possible, what steps would you take to achieve this?

3) Even if you get the offer, would you not end up getting fired a couple months into the job when they realise you're an idiot and know nothing.

suh dude: