They bought them years ago and now have thought about selling due to market conditions being favorable, or maybe something has come up that is forcing them to sell. 

To answer your question about maximizing profitability: I choose to invest for equity and forced appreciation.

Forced Apperception (BRRRR or buying at a discount) is also a hedge against corrections.

There are a few markets in the US where you are forced to look outside like LA, SF, NYC, Boston etc, but even for Chicago investors it does not make sense to invest in Milwaukee due to the added cost and complexity

It forces me to get real familiar with my business and how my properties are performing.

They force you to take instant bookings without any ability to screen guests.

such as by including affirmative coverage for forced removal in the loan policy. 

Forced Apperception (BRRRR or buying at a discount) is also a hedge against corrections.

If you put games out and they are all missing pieces and useless it will create situations for bad reviews and possible forced refunds on Airbnb. 

This is my way of not being forced to rent to the first qualifying party that gets a toe in the door.