Difficult likely to get rid of bad tenants and paperwork night mare.

The lesson is not about trying to time the market better; timing the market is difficult.  

Without naming any sources or the distribution ratio between the 4 mentioned mediums, it is difficult to determine from the user's end. 

REI is challenging, and if it seems easy or maddeningly difficult you're not doing it right. 

The second  problem is it is difficult to find people who will do preparation of the land for the mobile hand ,and also  I don't really know what is better/easier/cheaper...putting concrete pillars in the ground every 8 feet or putting down an asphalt or concrete slab.

It is difficult because each state has special requirements, making it tough to hardcode each variation. 

That would make it very difficult for you to make loan payments and/or pay the loan off.

Of course one can hire professionals with those skill sets, but for me and my family living in a new city where we didn't know many people, managing and budgeting for large scale renovations would have been a really difficult task when we were starting out our real estate journey while also navigating full time work outside of real estate simultaneously. 

That was my attempt to scale my real estate portfolio - it's just difficult in 2023 and 2024.

And every flip as one easy and one difficult transaction.