Philosophy and theory are good things only for people that have time in their hands and full belly - implementing an ACTUAL business is very different , today.
1) If you are basing your idea on what you read on forums and internet ,you're totally wrong. First,don't assume all the threads on forums are genuine. Second, you
see only the tip of the iceberg : people that come to forums, again, if threads are genuine and not started by fake posters, are usually people who WON'T spend a dime, freeloaders and usually have simple or non-existent problem except their laziness (want pre-cooked solution). And remember BlackST's DR law n. 1 : value of customer data tend to zero when DR cost > 0.
1bis) Problem no. 2 : it's easy to make copy / paste. Internet is full of copies of the same (wrong) posts/threads/pages.
2) Are you planning a "grey-ish" or "black-ish" business or a regular one ? Assuming it will be regular, you have to invest 50'000 to 100'000 EUR /$ to get started, trained and set up everything (in about 1 year), then you still have to enter the market.
3) At this point, if you have a street shop, you get "n" case , on these you have some good and a lot of bad / not recoverable, mostly because of user attempts . This, if you have a no data no fee policy ,will kill your profit margin and you'll just loose time.
4) You'll soon discover that the info you need or the tool you need for "that urgent case" is... the one you don't have at the moment. Will you then come here and ask for help ? Hmmmmmmm.....
5) 90% of the case is physical, nowadays. No, TVS and simple circuit repair (assuming it's simple) don't count and it will kill profit margin too.
Logical problems are only 10% and the revenue they bring is so low that in many case , if you have other things to do, you earn more refusing them. Law of the "big figures".
6) Don't forget to consider fees for tooling TS and consumables, like filters for clean room equipment (ouch !!) and eventually certifications etc. etc. . Ah, I forgot
TAXES.7) Finally, if you want to enter profitable markets like enterprise and hi-end , you need PREMISES as prerequisite and have to build reputation and references otherwise you are still at the starting point.
P.S. Les Brown, R.W. Emerson and co. didn't do DR.
