Actually, why not? Good luck finding enough fissionables to make a bomb, and you would do well to store it in a well shielded locker of some sort, lest you, your family, and your friends die horribly within a few months.
A tank is a better bet, but where will you park it? Where will you drive it? How will you pay for fuel, maintenance (for something so well armored the things break at the drop of a hat) and how may 105mm shells can you afford? No, the only use for a tank is the cool factor.
Oh, yes, I almost forgot. In either case you will be liable for any damage you cause with them, whether civil or criminal. Another expense nobody needs.
Proper, constitutional gun control. See how that works?