If you're a mobile developer, this almost certainly happened to you. A friend or relative makes you swear to secrecy about what he's going to tell you next. His secret idea will change the world and make millions. He comes up with the idea (usually like Uber but for X) and you do all the development work, split share 50/50.
Most people think that coming with an idea is hard, but it isn't. Everyone has a ton of ideas all day long, many of them ridiculous and some few genius. However, execution is the difficult part: development, marketing, building a company and so on. That sucks in every available time slot in your day as you try to make your idea into reality.
What's worse however is most of these ideas fail. Startups get a ton of investment money that is sunk into nothing. People quit their jobs hoping their new business will let them retire early. None of this really happens.
People are mesmerized by what they see in the media. A teenager who made a soundboard app makes millions and buys a mansion at age 17. Another makes thousands of dollars in ads from his YouTube videos or Twitch streams. However, all of this is a form of survivorship bias.
How many Twitch streams are watched by virtually nobody compared to the few famous ones. Pennies are made from most YouTubers who put ads up. The reality is that these successful people are the exception not the norm, they can almost attribute their success to luck.
I've seen people with no fame make excellent content and vice-versa. Producing good work isn't guaranteeing success. Not the best product is always the one that makes it to market. If we can call it that, fate, results in success.
However, to succeed, one must play the lottery game and hope to make it there. You can't beat the odds if you don't try. But don't approach the idea with naivety, but actually study what people want. Notice how informercials sell mundane things you never thought of and they sometimes make great success even if their products are garbage.
Think of a problem that you actually experience day to day. Something that bothers you and perhaps others. Maybe finding a solution to that would increase your success. Don't just imitate another streamer or blogger, because they succeeded out luck mostly. You need to do something novel that no one has ever thought of yet, and maybe, just maybe, you'll be making a few bucks.
When working on a project, your goal shouldn't be fame or money, but rather passion and learning. That growth is so much more valuable as the new skills you learn can be put into use somewhere else, maybe in a job that actually makes money.