When a player buys a pot in poker games, s/he does so in order to make their bet big enough for other players to call. By buying a large pot, what a player has in mind is that the bigger the pot gets, the less likely it for the others to call which may go against their playing advantage. To make a raise before the flop, a player can quickly buy the button to a desired size or amount that s/he feels is big enough to bet into the game.
This is simply because such a player wants to induce the others with a better position compared to theirs which will lead to a fold. If the other players who are close to the button fold, it means that the witty player has succeeded in buying the button. This seems to work well and better if you are closer to the dealer button at the start of the game. The whole thing all comes down to buying the pot with the hope that you can do so with less risk of being called upon and secondly, betting or raising with the hope to those players who are between the button and you will fold. The latter move will now enable you to play last in the next rounds.
