From the historians I’ve read, the thinking is that most preindustrial colonial projects including Russia were vanity projects by rulers with little strategic thinking. As for the USSR it seems the goal was twofold. Spreading Soviet ideology and giving the USSR the resources to be a global player. It seems with the Russian Federation it’s mostly about getting the resources to stay as a global player, but it the whole picture probably will only be clear in hindsight like any historical event.