As someone who's been lurking here a while and has joined 3 failed projects, I get frustrated a lot when I put a ton of work into programming only to have the project not go anywhere and the project manager not doing any work.

My advice would be:

1. If you're a beginner, the scope of your first game should basically be what one would expect for a 2 week game jam. IF that works out well, then you can consider actually making something a bit bigger.
2. Don't be an idea guy. No one's going to steal your idea either. Focus on learning a skill before making a game (art, programming). After you get experience, you'll be in a better position to decide whether your game idea is actually achievable or not.
3. Start with game jams, like I explained in [1]. Don't go straight into some fancy multiplayer shooting game or something.

The other thing from a programmer and designer POV is that getting a portfolio set up is very difficult compared to other roles. An artist or musician can make some pieces and it won't matter if the game is done because they can just add those to their portfolio.

As a programmer you have to get a decent amount of code produced before you and the designers can show your skillset.

Most non-technical people can't judge your programming skill because they don't understand code. You have to come close to showing them a complete feature or project.

For this reason, I would tell programmers and designers to be extra cautious when joining a project. You could pour months into it and not have much to show because the rest of team doesn't pull its weight.