Most things that people have to fix, happen in the first year or are discovered immediately after the purchase. It is already covered by 1 year dealer/factory.
Many of these things are easier to fix yourself than taking trailer back to dealer, leaving it there for weeks and bringing it back. Moreover, there are things that you SHOULD fix yourself because it boils down to replacing OEM cr-ap with proper parts.
After a few seasons things begin to break. Again, some of this can be fixed by owner. Read fine print, there is a good chance that it falls into "tear and wear" not covered by any warranty.