> Shouldn't the other international stakeholders pay their share
That is the direct Trumpian line: the US should pull out of anything where they are "being taken advantage of".
BUT even making "Is there any good reason why this money should come out of the USA taxpayers' pockets only?" the first - or only - question to ask is going about things arse backwards.
The first, the most important, question, whose answer overrules anything else, is: "Do we - the US - risk more costs by NOT having this programme?" (or "Are we getting our money's worth?" or "Will we really, really regret not spending this?" or a dozen other ways to ask the same thing). To which the answer is YES!
If we accept that the US taxpayer paying for this is in its own interests, should they kep it to themselves? Well, will that be cost-effective? Nope, of course it won't, don't be ridiculous. Bug hunting is a world-wide endeavour. If the US list is inly visible to the US, why would anybody in any other country ever bother handing over information they've found? Especially if there was any cost attached to finding it. So should the US pay the costs of all these bug hunters across the globe just to fill the US database? Is there a cheaper option? How about - just let the database be readable by everyone and accept submissions by everyone. Not only does the US then gain even more for its money, it saves on having to set up the systems to prevent global access whilst still allowing full access within the US: unless a Great American Firewall sounds like something that ought to be built anyway.
The bottom line is that it is far, far cheaper to run a globally useful system like this than not to run it. Even when you just look at the cost benefits of one player.
To risk it just because you want to ask "why should we be the only ones to pay?" is the absolute epitome of cutting off one's nose to spite one's face. It is putting paranoia and xenophobia before even bothering to calculate the balance sheet.
"But, but, everyone else is ripping us off! They should pay! It doesn't matter if we are acting solely in our own interests, if *we* are getting far more value back than we are spending, *they* don't deserve to get anything for free!".
Ah, the clarion call of the truly mean spirited.
And those unable to comprehend Soft Power and that they are getting back even more value than they have bothered to write into their spreadsheets whilst reading the above: there is a reason why, when buying a business, you pay for the Goodwill that has ben accrued.