That's not the theory. The theory is that all russian oligarchs serve Putin. They are not trying to gain access to Trump for themselves, they are doing it for the Country, I mean Putin
And I feel the need to tell you that I used alpha bank DNS theory sarcastically because it was thoroughly debunked. Well, not completely thoroughly because people who put it forward have not been investigated for apparent criminal bullshitting.
Don't be silly, barbos. You know quite well that Vekselberg has close ties to Medvedev, who is best known for his loyalty to Putin. He is one of the only oligarchs who was not shoved aside when Putin came to power and consolidated his control over private wealth in Russia.
I don't know whether all oligarchs serve Putin, but I suspect none are in a position to incur his displeasure. Vekselberg is probably not wealthier than Putin, but enough is publicly known about V's finances to rank him as the wealthiest Russian oligarch on public record. Who else could control the brand name "Made in Russia"?
As for Putin's fingers getting burned in the Cohen matter, that raid was not necessarily the result of the Russia investigation. Trump's Stormy relationship with a porn star had a lot to do with it. It was her lawyer who broke the news of the payments in public. And there is no reason at all to assume that Vekselberg was trying to buy access to Trump. You are quite right that Putin doesn't need this payment to gain access that he already had. What Cohen represented for Putin was what he thought would be a safe conduit through which to launder cash payments to the Trump organization. It gave Trump a slush fund to play with in matters such as paying hush money to porn stars, among other needs. For Vekselberg, this was low-cost influence peddling. Vekselberg is on the sanctions list, so it was also in his personal interest to help bribe Trump to work on that problem for Russia.