Maybe the reason it seems so ridiculous that there's thousands of troops in DC right now to protect the inauguration is because that's not why they're there.
What if they're there to protect DC from the angry mobs after they start banning guns, packing court, making new states and who knows what else they have planned??
It could go either way, they may be planning a mass genocide of Trump supporters for all we know and the troops are there to guard the Capitol while they do it without even knowing why they're there