It's true that if we could seriously boycott economic interaction with Russia we could stop Putin's military aggression without firing a bullet. The problem is that Russia, like every other country on the planet, is a cog in the wheels of the 'global money pump'. And the people who are benefiting most from that money pump are also the people in control of most of the governments on Earth. And they don't want those governments doing anything that would impede the flow of money into their bank accounts. They care a lot more about that flow of money than they do about the people living in the Ukraine, or living anywhere else, for that matter.
Also, most of humanity, all across the world, is now enslaved by this giant global money pump. They have to serve it, to live. So they, too, are not going to be inclined to let their governments do anything that would serious impede it's function, especially if they are going to be effected by it. Which is how greed and the fear it generates in everyone toward everyone else has come to rule humanity. If we could seriously impede the Russian corner of the great money pump, the Russian oligarchs would reign in Putin right quick. And the Russian people would applaud them for it. But to do that, the oligarchs around the rest of the world would have to be willing to accept some serious imposition on the flow of their own profits. And since greed is their only real motivating agenda, they are not likely to accept that imposition. And why would they? They don't care about Putin or the Ukraine. All they really care about is that flow of profits into their bank accounts from the giant global money pump. And it's not just the super-rich oligarchs, it's everyone else. too. Because money is life. And the lack of it is death. And everyone knows it. We are all enslaved by the giant money pump. Putin just happens to know how to be a successful tyrant within that greed based paradigm. Because the money pump likes warfare. Warfare generates lots of profit to the oligarchs, so long as it remains limited in it's swath of destruction. So neither Russia's oligarchs, nor ours, are going to do anything to stop him so long as he keeps the destruction to a 'reasonable' amount. Just as the US has been doing for many decades, now.