if they are looking to become foundation members, they should contribute to the funding also: they will have a good price for the iota they buy, I think it's normal they contribute to the foundation funding too.
They may very well do later on, but you have to understand that these are not small companies, they don't care about chump change. For them this is about being at the forefront of a brand new technology and working out how it can improve their business model down the line. Naturally it is in their interest to fund further development etc. of IOTA down the line, but as it stand right now *we* benefit the most from this mutual relationship.
I'm sure people will heavily invest in foundation when big-deal-buyers will be known. So indeed, if big buyers wait for the foundation to be founded before walking out the wood, we have a problem.
Anyway, the foundation is already well founded: how did you get the 50 million old iota number? is it a request of big buyers?
Then the people who are sitting on the fence is truly clueless, no ifs and buts about it. IOTA is already considered one of the major technological achievements of crypto, it's already 20xed pre-launch, it's already got huge companies interested in it. If those achievements are not enough to sway these people and instead they need some sort of additional 'appeal to authority', then they are literally dumb.