You have a really narrow world view. Just because some amount of money is big for you, it must be for everyone else?
An investment is not good or bad depending on the amount invested. I bet most of your 0.001 BTC investments are worse than this particular 100 BTC investment in terms of expected ROI and risk.
Yes my world view is really narrow because i dont give out 26.000$ to complete strangers which have no accountability and cant be caught if they run away with it...
The first rule of investing is risk control and that means that you must know the investment and the trustfulness of the owners before putting a dime in it.
Risking 0.001 BTC it wont make you rich, but it is for testing purpose, to see if they pay you or run away with the money.
The amount of investment is irrelevant to the chance of that person running away. I'd say for many things a higher investment makes it even unliklier that a person vanishes, because the amount of money he can gain from the investments is enough to make a living. A site that accepts microinvestments will most likely be only a hobby.