How do you calculate it as 1 in 3?
Having 25,000 attempts at a 12,500/1 shot is not the same as 1/3.
Add to the fact that the odds of 12,500/1 are calculated for all amateurs on any given hole. If you're on a shorter hole the odds will actually be less. Also playing the same hole over and over for 25,000 shots will also reduce the odds, unless your golf shots are truly independent random events.
For a pro the odds of a hole in one are closer to 2,500/1, and a low handicapper it's closer to 5,000/1 so it's not unreasonable to assume given all the above it's actually closer to something like 3,000/1 to 8,000/1 for most people on this forum as I don't think we have a lot of 54 handicappers.
25,000 attempts at an 8,000/1 shot. If I said you can choose heads or tails and then I will flip a coin 6 times and if your choice comes up once you get £2 million, but if you lose you go to jail, would you take it?