Start smaller than you think. A weekend farmstand or a home-based cottage bake is a real business, and it teaches you the same lessons at a fraction of the risk.
Do the math with pessimism. Assume half the volume you hope for and double the ingredient costs. If it still works, keep going.
Hours will be brutal for two years. Wake up at 3 a.m., bake until noon, plan and prep until 6 p.m. That's the job before you have employees.
Find the mentors. Every baker we know found someone who let them stage a few weekends. Ask. Most bakers say yes.
The romantic reasons burn out. The reasons that last are: you love the work of it, and you love feeding your neighbors.