If you run out of money, you may be forced to sell the property. This is why it is good to have a healthy reserve account and a plan for what to do when finances get tight.
Investors who do not stick to a lease are just inviting in bad experiences and rarely do anything good happen by being soft around enforcing a lease.
I see so many people get into the analysis paralysis state where they want to continually learn more before actually jumping in the water of investing.