I do agree with your assessment of the sizes of the talent pools in Russia, USA and China. Back of the envelope calculations don't support your assessment of the Bulgarian talent pools though.
Your assumption that the Bulgarian coaches have a feedstock of hundreds of thousands of lifters is very far from the truth - the whole Bulgarian population is considered to be around 7.3M people, which doesn't account very well for all emigrants living abroad. Out of these 7.3M only 16% (~1M) are aged 0-17 (I assume that 14-15 y/o is the usual age that a lifter starts training professionally). That means that at the moment there are around 100K teenagers (aged 14-15), out of which less than 50K are male.
During the past 20 years sports have lost a big chunk of their (state) funding and therefore the attractiveness for young uneducated kids have lowered substantially, further reducing the pool of athletes.
I consider the three most prestigious and popular sports for males in Bulgaria to be football (soccer), wrestling and weight-lifting.
I'm actually having trouble nailing down a source for where I got the 200k number. It was for total registered lifters at all levels, including youth, juniors, seniors and masters. When a sport is popular in a country, it's played at all ages.
Meanwhile the USA had, until Crossfit, about 3,000 lifters. Not a very big pool to draw from.
You correctly point out that state funding for Olympic sports collapsed some time back and that this removed the quasi-professional pathway.
For a similar reason, few athletes in the anglosphere who is naturally strong and power will go into weightlifting. They're playing gridiron or rugby. Those sports are popular and have lucrative professional leagues.
I usually leave doping out of the discussion because it's not a point of distinction. Most dominant countries have doping programs. It just seems as though the Bulgarians are particularly inept at planning their steroid cycles to avoid detection at international meetings. Or possibly Ivan Abadjiev doesn't care how he loses lifters -- whether through quitting, injury or doping charges.
Your assumption that the Bulgarian coaches have a feedstock of hundreds of thousands of lifters is very far from the truth - the whole Bulgarian population is considered to be around 7.3M people, which doesn't account very well for all emigrants living abroad. Out of these 7.3M only 16% (~1M) are aged 0-17 (I assume that 14-15 y/o is the usual age that a lifter starts training professionally). That means that at the moment there are around 100K teenagers (aged 14-15), out of which less than 50K are male.
During the past 20 years sports have lost a big chunk of their (state) funding and therefore the attractiveness for young uneducated kids have lowered substantially, further reducing the pool of athletes.
I consider the three most prestigious and popular sports for males in Bulgaria to be football (soccer), wrestling and weight-lifting.