For the sake of argument, let's pretend he has invented a truly clever and innovative improvement in antenna technology for cell phones, and furthermore, let's assume he knows enough about all of the other practical constraints in this area that his design can truly work not only in theory, but in practice, as well. I know, that's a stretch of the imagination...
He clearly has no capital, as evidenced by the fact that he needs to ask strangers to pitch in 70,000 (I don't know the units; I'll assume it's something within an order of magnitude or so of a Euro or US Dollar) for test equipment, and he's promising a rate of return many orders of magnitude in excess of what a bank would charge for a business loan, which tells me that he can't convince any banker of the worth of his project. Furthermore, he knows in advance that this test equipment will allow him to take his idea worth 4 million and turn it into an idea worth 100 million?
That makes no sense to me at all, but I'll suspend disbelief a bit further and assume he's absolutely right, and he knows in advance how much the testing can improve his idea, even though he doesn't have the wherewithal to perform the testing at the present time, so he can't have seen the test results yet.
My question is, how is he financing the intellectual property attorneys to property protect his idea worth 100 million? IP attorneys don't come cheap. I would expect the cost of obtaining the patent(s) alone would be at least as high as the cost of that test equipment, but the cost of obtaining such a patent is only the beginning. He had better have a healthy reserve of capital if he expects to defend the patent in court. The phone manufacturers have armies of well-paid patent attorneys, and they know the game well.
He also must be careful as he markets this idea to the potential customers that he takes all the proper legal precautions to prevent them from stealing his idea, while allowing them to see enough of his technology so that they can understand why they would want to pay millions for the right to use his idea.
Without good patent protection, there is precious little to prevent a mega phone corporation from simply copying his innovative antenna design and paying him nothing. If he complains and sues them, they'll drag it out in court until he runs out of funds, which apparently won't take long.
The only way a phone manufacturer is going to pay millions for an idea, even a great idea, is if it gives them an advantage over their competition, meaning it must be something their competition can't copy easily. For something as obvious as an antenna, that means it needs enforceable legal protection -- it can't be just a simple trade secret, because it's too easy to analyze an antenna's geometry and copy it.
Just to be clear here, I'm confident he doesn't have an antenna innovation worth millions. I'm just saying that if he did, he would need a lot more than test equipment to collect any money for his idea.