The Russians always have to one up weapons, no matter how stupid or useless they are. Tsar Bomba is an excellent example. For what possible reason could anybody need a 100 MT bomb? A 10 MT bomb would be massive overkill for a large city.
This is just more of the weapons propaganda that we saw during the Cold War. Bigger submarines, bigger nukes, bigger rockets, bigger artillery, etc. What is Putin going to do with it next, parade it in the streets?
Well, I guess the women and perhaps some of his Generals like parades, so there's that, but when you look at this quote from the related Reuters article:
"It (the bomb) will allow us to safeguard our state's security and fight international terrorism in any circumstances and in any part of the world," Rukshin said.
it says "Chechnya" to me, at least. From Putin's perspective, this sort of thing would be perfect to swat down any insurrection in that arena.... a massive, impressive fireball of a "secret explosive" over a wide area that would tend to have a 'deterrent effect' on future uprisings, no radioactive fallout, quick deployment and minimal international diplomatic problems, compared, at least, with using a nuke..
If Tsar Bomba had detonated at its maximum 100 MT yield, it could have resulted in a fireball almost 6 miles across. Lethal effects would be felt in an area the size of Maryland. Still, such destructive power would be dwarfed by a relatively small asteroid impacting the surface of the Earth.