I did some insanely dumb things when I was 17, and there was almost nothing I didn't know. At that age kids think that if people don't agree with them it is only because they don't really understand the situation or they're afraid to try things a new way. If I can give you a little advice it would be to hand out the first 2 or 3 thousand of your fliers yourself so you aren't on the hook to anyone for anything. See how it goes, see what your response rate is, and see how you deal with the 15-20 calls that those fliers should get you. Ideally there is nothing dated on those fliers you had printed so once you have all of your systems in place for dealing with calls, subs/employees, complaints, billing, insurance, taxes, new bids, and on and on and on, you can then roll out your second round of fliers. Dropping even 5 thousand fliers in the first few weeks of business is WAY too many. Be careful and don't assume because the math works out and the numbers look exciting that you can just scale your new business has high as you want to. There are countless variables and each of us discover even more of them all the time. There are very few uneventful, average weeks in this business - especially at first. Most of the surprises aren't the kind you hope for. In my first month in business (1995) I wrecked my truck because I hadn't pulled a trailer before and didn't realize it would take A LOT more time to get stopped on wet pavement with a full load of wet grass in it, and later that month I hit a mostly buried steel stake with my brand new (financed) mower while cutting tall grass. This resulted in a bent drive shaft and over $400 in repairs. Fortunately the very kind owner of the mower shop gave me a loaner to use while they were fixing it. You probably wont make those mistakes but there WILL be others - I can promise you!
Get yourself up to 7 or 8 lawns a day, and do the work yourself. That will still leave you a few hours a day to further develop your business and research questions that are sure to arise. It isn't nearly as exciting as the anticipation of what will happen when 50,000 fliers hit the streets, but it would be loads safer and smarter.
I think most people would agree that they knew a hell of a lot less when they were a teenager than they thought they did. Chances are you aren't that much different from the rest of us. Try to ask questions only when you want to hear an honest answer. If you already know what you are going to do, just do it and then feel free to share the experience with others when you see how it turns out. If you don't know what you are going to do and you choose to ask for help, try to be open to criticism and suggestions. People are much more likely to try and help someone that seems to actually want to listen.
Best of luck, and if you do still decide to drop all 50K fliers with the help of people that you hope to be able to pay, I'd be very interested to hear how it all goes. Either way it should be one hell of a story.