through often not on paper, but in practice, like the people which can throw rocks in your path do that less likely
in the end it's a question of job (in country you want to move to), money/liquidity, and moral restraints you have.
Like e.g. buying yourself citizen ship through an arranged marriage should be something like 30k-50k€ depending on EU state, context etc. And that is if you go through organized crime rings which take a cut.
And if are rich there probably should be a lot of more legal-ish ways to get citizenship. Some countries outright allow buying citizenship, but I think besides the "buying" cost you need to be quite stacked.
And if you have good job qualifications you might get a job in the EU -> long term right to stay -> and then find one way or another to convert it to citizenship. It's probably ethically most upright but also hardest path.