Those who think this is a “kook theory” have either forgotten or never understood how the KGB worked. It has always been normal for intelligence agencies to develop assets over decades…and the richer and more powerful the asset, the more effort that would be put into attracting or otherwise compromising them.
When considering the enemy, it is the oldest mistake to underestimate them, to assume what the enemy will or won’t do.
People who think that recruiting or compromising Trump was somehow beyond the scope of the KGB’s mission would do well to look up Kim Philby and the Cambridge Five. Compromising someone both rich and influential like Trump — especially with what was even then his well-known predilection for girls on the younger side — would have been not only desirable, but relative child’s play for KGB agents…and for the ex-KGB colonel who is the de facto dictator of Russia today.