A single-digit percentage of rides are point-positive rides by bike angels, so it's not nothing, but it isn't huge either.
Bike angels definitely have an outsize impact on the system compared to the number of rides they do. To illustrate, we have an internal leaderboard where I am regularly the employee with the most point earning rides (because robert_halo opted out of the leaderboard after having been the top dog for months) but even in weeks where I have earned the most points, I tend to not have the most rides or the most unique stations visited.