My assumption would be that he hoped he could at least become a martyr for the Russian people. It is one thing to be accused of crimes, and flee your country forever, it leaves space for Russians to think “well if he is an innocent man, why is he on the run? If he wishes to represent this country, how can he if he flees it?”. Maybe he hoped that by coming back and facing the ridiculous charges, it could at least give him some credibility with the citizens who would maybe see the absurdity of it all, and maybe spark some kind of political unrest. It obviously didn’t work, but in the face of the hopeless political situation in Russia, can you blame him for trying?
The difference is that a cars only purpose isn’t to kill or maim. There are very obvious positives to having widespread access to cars. I can point you countries where there is not widespread access to guns that do not have these problems. Can you point to any that have guns as accessible in the US that don’t?
Because I know your next argument will be about knives or cars again, let me address both of those: A knife is not nearly as deadly as a gun. You can at least run from a knife, its much more personal so less people are willing to use it, and you at least have a chance of fending off the attacker. Against a gun, your only hope is that they miss. And regarding cars, you’re right, they can be used as a weapon! Do you know what solves this issue while also still allowing people to commute? Public transport! Im glad we agree cars are an issue, and that public transport is needed.
Since you clearly don’t think everyone having grenades is ridiculous, how about rockets? Missiles? Should any citizen be able to obtain those too? Mustard gas? Nuclear weapons? How far are you willing to let that go before its obvious the cons outweigh the pros?