I finished a game of League of Legends where I earned 25000g. At the end, I had ~6000g unspent, as I already had the boots I wanted and 5 top-tier items. What am I supposed to do with all the rest?
The main thing to purchase would be Elixirs. If you purchase an elixir whilst you have all 6 items occupied, you'll instead automatically consume the elixir and gain its benefit. The fact that the benefit persists through death is merely icing on the cake for what is otherwise just some extra stat bonus that you don't need item slots for. With 6000g, you can buy a very long duration of elixir benefits.
A less savorable option would be to swap out items for other options. Perhaps to account for a shift in how the battle is going, or to try out a new strategy. Usually, if you're swimming in gold, though, you don't need a new strategy. Nevertheless, sometimes you think that swapping for, say, a more push-oriented item in order to just end the game, for example.
When I have that much gold and 3 elixirs on me, I sell my boots and buy onw of the following items:
- Trinity Force(if I dont have) or Phantom Dance for AD champions
- Lich Bane for AP champions
For my gameplay these items are more useful than boots, because ussualy I dont need to rely on movement speed in late game, these items can give me enough movement speed to finish the game, plus they add more chance to win a team fight IMO.
(when Im playing a tank I switch the boots for FoN or Trinity (if I bought FoN earlier))