Could be just a fork, could be multiple pieces of silverware, could be a whole roll of silverware, whatever. Plenty of caterers have already chimed in with how often it can lead to dropped plates, which they then have to clean up. That's an inconvenience to the person who dropped it, the caterers, and everyone around them, is it not? Surely a greater inconvenience than having to wait to get your fork or whatever or just say excuse me

for the sake of your convenience at the expense of most others; that's selfish

One of those worse things being when you have to also carry your full beverage cup because all the drinks were also at the start of the buffet line. And even worse being when you have to juggle two plates because your partner is in the wedding party and someone decided to do all the group photos before letting any of them get their plates and the food is running out very fast.

Say, "excuse me, I just need to grab a fork real quick." If they don't move, say it louder, and then just push your way through if they're ignoring you. The alternative is making everyone have to juggle way too many things through the whole line to make things easier for you and maybe a handful of others.

Plus if it's a long buffet, you don't want your protein getting cold(er) by the time you sit down, so makes sense to grab it last. Assuming it's being kept warm on the buffet.