Explain 5 point Blot Blunders to a Beginner

Getting hit isn't a big deal here especially if gammons don't hurt you (you really should say the match length/score when posting a position). You're already down so much, it's not like you are winning a straight race when you don't get hit. In fact if White manages to escape his checker, the third checker back could you help you hit later. Since building a good prime is super important here, the risk reward calculation strongly favors playing boldly.

Also you have your 3 point which doesn't go well with the 9 -- points 6 apart from one another are sort of redundant since they don't form two points in the same 6 prime. If you had the 4 instead of the 3, your play isn't so bad.

In the second posted position, using the 1 to move the spare to the 7 instead of the 8 accomplishes nothing. You are still unlikely to win without containing the white straggler and you need the 4 and 5 points to do so. You are unlikely to make these points with safe play, so slotting the 5 point accomplishes something — it makes it much more likely that you’ll make the 5 point. If you are hit, that is not great, but if you hadn’t slotted, it means white was likely to escape anyway, which pretty much is just as bad.