In my opinion it's preferable to wager 500,000 satoshis to receive 1 GT than purchasing each of them for 25,000 satoshis, though.
The point it that if you do "reasonable" decisions, you will end with more than 475k sat if you wager 500k. Which means that you not only received 1GT (additional benefit), but also you have a "base" profit. You just need to decide what to do with 500k sat, while many "small" players do not bet so much - anyway I think it is quite easy doable in a few months.