That's a cool way to get people interested in the platform! It is easy enough yet brings people and cryptocurrency together. Still, it wasn't a worse time to buy Steem. Some people invested back when Steem was 6$ (was it? it feels like it has never happened).
And I think you could have tracked the increase per month to give you a better idea for the break-even point instead of calculating big chunks that only give you a current value.