Many years ago, I did a lot of homework problems just for the fun of it. If another class had interesting homework problems, I did them too. There was Internet but no web. And people didn't spend their time asking other people to supply solutions. What cheating there was, was probably limited to people picking up discarded printouts and trying to figure out if they could use the printed code fragments.

A long time later, I still think it is fun to solve problems. I don't really have the time to do it, but if I see a programming challenge somewhere, I have a hard time to resist finding a nice solution.

But the driving force is the joy of finding a solution I'm proud of. So there isn't really a need to post any code - it's the path to the solution that is the joy. Alas, the same goes for hardware. I like to design devices, but the end products tends to end up collecting dust.

One thing with web forums is that whenever someone asks about a school problem, there is always a number of people who are at a level where they are just about able to solve the problem. So they have a fun time solving the problems. But at the same time, they want to show how clever they are, by posting the solution to the almost impossible problem. That is sometimes a good thing to do. Sometimes it isn't. Quite often, the OP has asked the wrong question, in which case the answer to the question isn't really useful. That is one of the reasons for the large number of questions that often follows a help request. Most of the time, the original problem is quite simple, but the challenge is to figure out what the original problem is instead of figuring out strange work-arounds.

But what I think is most rewarding, is when someone leaves a thread, having gained new tools making them able to solve similar problems on their own. A hobbyist may be able to limit their own projects to subjects that are well covered on the net. But an R&D engineer just need to collect all the relevant tools since there is no time to get stuck at every new problem and then have to desperately find a web forum to help out.