If you said wholesale because you need some 'faster' cash that's also ok.Just know that take all of those business models take laser sharp focus in each discipline to really get traction.Bouncing around business models is the sure fire way to get frustrated.  

Exert the discipline to do things outside your comfort zone and make it habit to do so.One of my adopted mentors - Robert G.

I'd verify that they bill late fees to tenants up to the date the money is deposited to your trust account with them - it will make them more disciplined, too.

A college degree provides discipline.

It is not their fault as they are not taught that discipline.

What lock should I buy, is Airbnb better than VRBO, etc)The former is probably the realm of good startup basics and financial discipline. 

Even if it only amounts to a few hundred or maybe a few thousand dollars in the whole year, you're building discipline.

I wish I had your discipline at 23

You will see they are investing in the strongest markets, have great broker networks / access to deals which is critical in a highly competitive market, can raise significant capital to take advantage of scale, more disciplined / conservative underwriting models, have simple well thought out business plans to increase the properties value, using fixed rate 10yr loans to take advantage of still incredibly low rates historically speaking and use more sophisticated tool sets to help understand how fluctuations in occupancy, rents, etc may impact their models.  

Be disciplined during the auction.