Mmmm. Confessions of a window cleaner...(the reality)
Well now David,
I am by no means the last word, but, I am into my 19th year window cleaning.
From what I read here I am in the majority, a new wfp user.
You are old enough to know that most, if not all manual skills take 3 - 5 years to master. Trad window cleaning took me at least 3 before I could honestly say, "I know what I'm doing, I'm good at this now." Trouble is, after many years it becomes repetitive, and you sometimes take for granted how much you have learned, until you meet a beginner and try to tell them what you are doing! You realise how much you know about, albeit, a mundane task.
So lets start by knocking down your reasons:
1) It's the best earner without qualifications. 
?How long have you been cleaning windows? If it is more than 3 years you have serious unwritten qualifications, that you have risked your life to attain.
2) You are your own boss. ??Sorry to disillusion you mate but, far from it! Now instead of only one boss, everyone is your boss!
3) I like the customers. ?I got news for you....They like you as long as you do what you are paid to do...If you don't, they will not like you. Now don't go sentimental on me.
4) Sorry mate wrong again. If it is getting easy remember, it could be because: you are getting better at a difficult job, you are getting comlacent, you are getting lazy, it could all go wrong any day.
No. 4 has not exactly turned on it's head. Ladders are no nearer becoming extinct than the paperless toilet! Just as we need proper cleanliness in the bathroom, we need safety on the ladder.
So, there is a load of good advice on this forum. It seems to me most are still doing their "apprenticeship". You are in good company.
I have studied wfp for about a year, worked with a friend, done it myself for 2 weeks.
I have learned, like everything in life, there is advice and.... advice. You have to sort what is good for you. You will make mistakes. With trad w/c the mistake of a wrong purchase might cost you £20. With wfp the mistake could cost you £200!!
But it is a big bonus tool to have in your kit.
Do not be naieve. There are a lot of guys that just want your money. They all believe in themselves, of course they do!
Read back posts on forums carefully...again and again, like in a library. A useful reference, but not the last word!
If you have a wife who you can trust as your advisor, listen to her carefully. If you can't convince her, don't bother trying to convince anyone else....(just my opinion).
finally, for now: What would you think if someone said to you, "I've got £50 spare, is that enough to get started window cleaning?" Well, £50 doesn't make you a windowcleaner! But when you are a windowcleaner £50 will get you a few good bits of equipment. Likewise, I am learning fast, £1,000 won't make you good at wfp, but learn as much as you can first at wfp, then you will soon realise you need more like £2,500 to get the kit you need.
Finally, finally...Get someone who can spell and articulate for you, so that you can promote yourself and explain yourself in print.
That's all for now, because I'm bored, and it is Sunday night. All the best.
Pj