your not even a good apprentice never mind businessman,listen to the advise your not ready to go it alone get a few more years behind you then think about it while earning a decent wage without the stress of worrying how to pay it
the term is realistic not negative,what experience you got installing/servicing/selling/pricing jobs up have you got years of seeing customers and giving them a service you can promise to maintain if they come with you etc etc
the thing with whistle is the years of experience in all fields before he went alone,being an apprentice you won't have that head start,walk before you run