PUtin in smart - he knows that the world will be in trouble with our oil, gas and wheat. So nothing would happen to them if the whole world would turn against them.
The bold parts are where you are wrong.
The reason why Russia doesn't care about the sanctions is because the "whole" world is not turning against them. Essentially what you see today is the result of decades of stupid policies in the West. Did you even know that at some point Putin wanted to join NATO!!! They showed him the middle finger.
Then they couldn't even create any alliance against Russia or China for that matter, not just that they created more enemies among countries that could have helped oppose Russia hence creating a polarized world where 2 blocs are created each opposing the other.
Take Iran for example. It has the largest existing oil tanker fleet with the biggest capacity and also has one of the largest oil and gas reserves.
What's the relationship of the West with Iran? terrible
What's the relationship of Iran with the East? best. In fact the biggest Chinese economic plan (one belt one road) is possibly only because of Iran which is also a member of SCO, the biggest economical alliance in the world.
Imagine if EU was independent and never listened to US and improved relations with Iran more than a decade ago. That simply meant they would have never been mainly relying on Russian energy and Russia could have never used it as a weapon against them!
Even today EU has to desperately buy Iranian oil at a much higher market price since they are buying it through middle men. Fun fact: the Iranian tanker that Greece stupidly seized (that led to 2 Greek tankers being seized by Iran) was carrying Russian oil to Western Europe.