Funding agencies these days fund people who get PhDs.

To get a PhD, 90% of the time you need to generate a meaningful result of some kind within a limited time horizon. Scientists who go big and create nothing do not graduate and do not get funded later.

What some of them do learn to do is to manage several projects at the same time. They diversify, working on some big ideas which may fail, but insuring a steady stream of results by also working through some lesser issues with a higher probability of success.

It's true that you can have a career stringing together nothing but small wins, but contrary to popular belief, the funding agencies (who rely on PhD scientific peer review committees) do fund many "high-risk, high-reward" projects.

In the private sector, for example, drug discovery projects have a vast failure rate but are funded nonetheless. Science funders do understand the biases toward career safety and are trying (imperfectly) to adjust for them.