“Will this be on the test?” is the question that students often ask to decide if it's worth their time and energy to study. Being prepared for test by not wasting time on things that won’t be tested and memorizing the things that will be minimizes the risk of failure on passing tests.
Project-based learning on the other hand encourages students take the risk by doing something that's not guaranteed, the things that may not work. When students view risk-averse as an assurance to pass tests and get better grades, the nature of project-based learning is an opportunity to do the opposite by exploring uncertainty and trying.
When the definition of failure isn’t about the outcome but not trying, we see risk in a very different light. Both have advantages and disadvantages, but one helps students build resilience while the other one doesn't.