Bulgaria has had bad luck for over a hundred years. Chose the losing side in both World wars, and then ended up a Communist satellite state of the USSR for decades. To top it all off: was then offered the chance to stay with Russian Federation post 1991 rather than pursue the EU, with near free Russian energy gas/whatever and picked the EU which enabled corrupt officials to sell off various companies to their friends. I visited several times, recently and the pot holes in Sofia are a joke. Even in the smooth fluffy car I was driven in, it felt like driving though the dirt jungle roads in.. Well, that's my experience, anyway. Mansions popping up on the way to one of their main mountains; with money that should have gone on infrastructure and roads. Nice cafe half way up, though.
Forgot to mention the Ottoman Empire issues they had. Place has been at the forefront of, "for fks sake" for centuries, actually.
Luckily in Russia state companies were never
given sold for a symbolic amount to friends of Putin

You know, like banks, chemical companies, and energy producers.
Corruption and Bulgaria / Rumenia, yep. Highly corrupt shitholes.
But compared to Russia a bit less shitty holes.
(They should never have been allowed into the EU, but the euromaniacs are to dumb to wipe their won asses so of course they could join).