If you have $1M with you and you buy Bitcoin for $50k and sell it for $55k then you can make that 10% profit alone but surely behind the scenes there are other people who buy your Bitcoin for $55k or above it and if those people don't but it for higher value then you may not earn any profit that way.

I know even the top leaders of the world who have achieved so much success in their lives couldn't do that alone because they always need to support of the people otherwise they won't be able to gain any reputation without others support.

However, in financial terms when it comes to trading and investing then you can do it alone these days and no one's direct contact or support is needed to gain profits by doing that. But if you follow traditional business models then you may need buyers and many workers who may help you to secure more sales.