Many inventors who think they have invented the next best thing since sliced bread, have not actually invented anything real unique, or real marketable. Some are close, but ignore relatively small details which need to be taken care of before their invention is real marketable. Some have something big, or big enough, but the bottom line is that there are limitless new product opportunities and they require a decent amount of investment. A company willing to truly partner with inventors, and go in on real, meaningful partnerships with them, must be very selective or else it is a losing proposition.
Look at it this way. Do you have decent credit? Could you develop decent corporate credit if you tried? Credit is harder to come by now than years ago, but many who complain about not having the cash to do what they would like to, are not usually willing to use credit as a solution. If you are not willing to risk your assets to commercialize your invention, why should someone else want to invest their hard earned cash in your invention. Of course, percentage-wise, someone else has less to lose. But they also have more options re: where they can spend their cash.
Any notion that suggests companies should be willing to help inventors without expecting financial success in return, is obviously false idealist. After all, if making money isn't important, why bother commercializing your invention. Just get the word out and hope someone steals your idea.
Coming from nothing, or close to it, and wildly succeeding nonetheless is challenging - but its been done before. It might seem like large companies are at an unfair advantage compared to the individual inventor - but if you consider the amount of time, effort, and money that was likely involved in creating such leverage, that is not necessarily the case. Wal-Mart, for example, started out as a single location mom and pop retail store.
Intelligence doesn't always translate to success in any area of life because intelligence doesn't necessarily equate to balance. Balance is key. When you are intelligent, it is still best to find other intelligent people to work with whose intelligence complements your own.