The short version
Before rolling or raiding, decide how much cash must remain for protection, inspect the base that currently holds your valuable pets, and avoid leaving simply because another base looks tempting. A good defense plan reduces exposure; it cannot make the base impossible to raid.
Build a Base and Steal links economy and risk more tightly than a normal tycoon. The same cash that can roll another pet may also be the buffer you need before protecting what you already own, while leaving to steal exposes your own setup. That makes defense a spending decision and a movement decision—not just a building layout.