The thing is chipleader can play bit more loosey-goosey(/they get right odds to call you with X hand) especially if they dominate you on the chips, so that is partially the reason why it might feel like they are dominating those all crucial all-in hands and you will suffer a bad beat from inferior hand.
Luck or chance doesnt exists neither in poker nor in mundane world .Its all about past deeds ("karma").Its misnomer and inability to identify hidden cause behind result ,For infinite sample size real world value has to converge with expected value that nullifies any chance or luck aspect of game ,As we are so concerned about short term outcome thatswhy we are reluctant to acknowledge that variance is part and parcel of game in short term ,
I think it just feels that way because chip leaders can put pressure on everyone, and when they get lucky in an all-in, it hurts even more. If we get our money in with the best hand, we just have to trust the math and accept that variance is part of poker. Over time, making the right decisions is what matters!