Ask HN: how would you turn this idea into a business?

I have a thoroughly validated concept/idea and I'm looking for advice on how to really develop a business out of it.

"Thoroughly validated" means I have 3 years of history where 10 close friends/family members have been on board as customers. Over that time, the revenue model has proven to be absolute.

The revenue model is basically a financial service. Revenue is generated for clients based on a few transactions per week (without going into transaction specifics, just know it is legit). Each client grosses ~$90/month, I usually take 50% for about 10 minutes of my time. This revenue rate has proven to be fixed over time.

New client requirements: - the biggie is a power of attorney (giving just the proper permissions to make the transactions on client's behalf) - also $200 is needed to fund a couple of accounts; I am willing to subsidize this and be paid back through future earnings - generally need to open two accounts with specific US financial institutions

I'd like to scale this up to 50-100 clients and see how things go. However, I'm not sure how to market this to people outside my "first ten." The POA and low client upside certainly makes it a tough sale and generally I don't know how to talk about it without people assuming it's some kind of get rich quick junk or a scam of some type. How would you get more clients?

Thanks!