Depends on what your criteria are… that may be true for mild and asymptomatic cases but if your concern is severe case and hospitalization the numbers are 8, 35, and 200 per 100,000 for boosted, fully vaxxed, and unvaxxed. If your concern is death the last numbers I saw were .1, .8, and 12 per 100,000.
Personally I’m not very concerned over a mild case so my focus is on hospitalizations, and I felt the difference from a 8 in 100,000 risk to 35 in 100,000 risk warranted a booster, for those who’s primary concern is staying alive the difference from .1 to .8 in 100,000 is a harder decision.