This is really funny because one of my friends from high school was a Marine and he did the exact same thing. Like literally he would talk about each split of his runs in the same manner and how extraordinary it was. He’d always talk about how he would run 16 miles at 5:30 average and he would finish the last mile in sub 5:00 (his mile PR was 4:50).
So I called him out and said let’s do a 9 mile run together. He started out fast in 6 minute pace which I knew he couldn’t handle but it would be a good training run for me. Shortly thereafter the pace slowed... to 8 min pace... 9 min pace... and he even had to stop for several minutes to catch his breath. I asked what gives? You can run 16 miles at 5:30 pace so 5 miles should be a cake walk... he had plenty of excuses such as it’s just a bad day. Then after crawling for 7 miles he sprinted the last mile in 5:15 and was proud of himself. I was like... you ran a 6 minute mile... took 7 miles of rest... then ran a 5:15 mile. That’s not good.
I even found out through other friends that he would go to parties and say his mile PR was 4:09 (which was mine) and he would tell people about all of my medals and top finishes as if he did them. He knew my life story so it was easy for him to just pretend it was his.
Long story short, these Marines are crazy.