Not all acquisitions are created equal. It's really very situational.
To answer the larger question you seem to be asking, a company or technology needn't generate a profit to be valuable. This seems counter-intuitive, but it's true.
To a certain extent large companies outsource risk-taking and innovation to startups. That kind of thing is just incredibly difficult to produce within a large corporation. If a company solves a problem a big company has it may be acquired; regardless of its revenue the founders have created something of value in this scenario. The acquiring company will pay a premium for something that's successful, because that means they don't have to spend time and effort constantly building things that fail. Think of it as anti-portfolio theory. VCs invest in 10 companies knowing that the majority will fail, because one or two successes will make up for all of the failures. Big companies buy the one or two successes because that means they can avoid the eight or nine failed projects.
It's entirely possible that the companies being acquired never generated any revenue, but are very valuable to BigCo, and BigCo pays a corresponding price. That is a success.
However, acquisitions aren't all good (nor are they binary). There's a spectrum. On the low end is a terrible acquihire, in which the acquiring company basically buys the startup as a hiring bonus for the people it wants. When this happens, the numbers aren't great; usually investors will lose money or make little enough that it's negligible. Remember that VCs really need huge returns on a few companies (ideally one company returns the whole fund), so even a company that returns what the investors put in plus or minus 100k basically go into the same "failure" bucket in the mind of a VC. The founders become employees with a biggish signing bonus (selling the company), and the acquiring company basically calls the acquisition price recruiter fees. That, in my opinion, is a failure with a soft landing.
On the other end of the spectrum is an Instagram-type acquisition in which the company is extremely valuable but it makes more sense to team up. Of course, this doesn't have to be a consumer product, but Instagram is a great example. Instagram never made a dollar, but in retrospect it looks like $1B was a great price, because Facebook will be able to generate way more than that utilizing Instagram's users and platform.
There's an entire spectrum between these two. Without knowing the details of each deal it's difficult to say, and everyone will pretend like it was a huge success regardless of what's happening. So to answer the question: Yes, a startup can run at a loss, be acquired and be a success. It can also run at a loss, be acquired, and be a failure.