There is no doubt a lot of corruption in Ukraine. I don't know if the $800mm figure is accurate or not. In either case, it does not change the fact that he is the elected president of Ukraine.
Particularly coming from Putin. The guy is got assets all over the world and, allegedly even a full sized real-emperor like palace in Russia.
No no, Putin isn't rich at atll, according to his officilal disclosure. How he can lie to us:
https://qz.com/1594989/vladimir-putins-financial-disclosure-claims-little-wealth/Vladimir Putin’s latest financial disclosure has been posted on the Kremlin website, showing the Russian president earned roughly $135,000 in 2018 from his official salary, a military pension, interest on savings, and investment gains.
Putin reports owning an 830 square-foot apartment in Saint Petersburg, along with a 193 square-foot garage, as well as use of a 1,600 square-foot flat in Moscow. He claims to have two vintage Volga GAZ M21 sedans (in the $14,000–$16,000 range on eBay) as well as a Lada Niva SUV (which starts at about $6,800, new) and a retro-fabulous Skif tent trailer, which goes for about $900.
Putin has a lot of money. In the billions of dollars, although much of it is likely currently inaccessible due to sanctions. A good deal of his money is held by family members and is not held directly in his name. It has been argued that if the West were to disclose the scope of Putin's wealth, that he may lose many of "normal" Russian people.