You can start a betting scheme where you charge all your members �10 to pick them 3 winners in a 10 horse race, or you give them their money back. You get 100,000 members and you have �1,000,000.
In the first race you assign 10,000 members to each horse, only one horse wins, you pay back 90,000 members, you have �100,000 and 10,000 potential winners.
In the next race you assign 1000 people to each horse, only one horse wins, you pay back 9000 people, you have �10,000 and 1000 potential winners.
In the last race you assign 100 people to each horse, only one horse wins, you pay back 900 people, you now have �1000 in your back pocket and 10,000 mugs to do the same next week.
Do this enough times and you have yourself a million. That'll be �50 please.