mostly, control of the situation. In the case of an extreme disaster you may not have access to a bank or safe deposit location. That being said, casino safe deposit boxes are better than banks as there is 24/7 access and security, and a lot of anonymity.
If you do put a safe in your home, scope out the best ways to secure it using its hardware, usually long bolts through the back, sides and bottom. Check fire ratings as well and then also look into fireproof pouches & good old ziplock bags inside for added security.
Best advice I ever got from a detective is to hide your safe and valuables in the kitchen. It's the last place burglars look since most people put a safe in the bedroom, closet or office. Kitchens are too fiddly to look through what with all the gadgets and things we typically store in there.
I installed a safe in the kitchen of a client in the catch-all & tools cupboard over the wine fridge and blocked it from view with the tool box. I chose that location because it anchors to a supporting wall of the apartment, took the guys hours to drill the holes for the bolts and we have to stand on a small stool to reach it with any ease. Considering how rarely it's needed access to, it's perfect! (plus the client is rather tall, easy for her)
The other option I considered was in the base of the cupboard in the island where it would be blocked from easy view by crockery and a shelf base. I nixed that option because the sub-flooring is wood though.