In fact, there is already an answer to this question. It was given on Twitter by Georgy Alburov (an employee of the anti-corruption fund - an organization that is equated to a terrorist organization in Russia): https://twitter.com/alburov/status/1497295164892581891
These guys know a lot about how corruption works in Russia and understand what can really hurt Putin. All of Putin's best friends became billionaires when he became president, so sanctions should be directed not against ordinary Russians, but against the business of Putin's friends and government employees. I am sure that Putin does not care about the problems of ordinary Russians, and many of the sanctions imposed by European countries are just an excuse to say, "look, this is confirmation that these countries were at the same time against us, which was required to be proved." Putin is not afraid of the isolation of the country, he and his friends are rich enough to live in isolation for centuries and feel comfortable at the same time. The dude from the anti-corruption fund proposes to ban the supply of elite furniture for Putin's palace in Gelendzhik. They know which European companies are doing this, so EU just need to consult with Alexei Navalny's supporters about the sanctions.