No. 0->100 is not easy (I know from my own experience), but it is a realistic goal and you can get there slowly. Adding even one user every weekday, you will get to 100 in six months. But, and this is a big one, if you support your users well, you will get referrals -- which is the best way to grow.
My whole point is to go for recurring revenues, and, aim for slow, sustainable growth. If you want to go for 10K users, you will need funding. And, that will be a much, much riskier path.