They can make money but from what I've seen your more in the customer care and takes more of your time.

I would get some professional advice including a PM company in Sacramento (even if you continue to self manage) considering your entire financial picture and future goals.

-Decide between fixer-uppers, which offer customization and appreciation potential but require more work, or turn-key properties, which provide immediate rental income with minimal effort.Hiring a Property Manager:-A property management company ensures efficient marketing, tenant screening, rent collection, and maintenance.

I find it unlikely that one could build a house out of a shipping container cheaper than one could build a stick framed house.I work for a custom home builder, and we are a union shop.  

After experiencing different types of inspections with all kinds of properties from custom builds to existing, it all depends on your end goal , I highly suggest you reach out to a team, really strong team such as @Jorge Vazquez.

I get what your saying if your 30 yo .. but I think its a different picture if your like me late 60s..

He put them on the mls with the crummiest of pictures and not even with the new landscaped backyard.

You must asses if they are they the weekend weed smoking warrior or are they number 1 customer from Breaking Bad. 

Understand it's a business not a RE pursuit meaning make sure the experience is #1 for the customer.

People online like to paint rosy pictures about how much money their short-term rental makes.