I think it's more a frustrated acknowledgement of how a racist and sexist system has made it so those who are not white and male have to work a lot harder to get the same recognition, jobs, money, appreciation and status then white men do.
The wage gap is an example. Two people doing the exact same job and yet one of them gets paid more for being a dude.
It's glaringly obvious if you have a straight married couple and they both have the same job. I know a couple who have the same job and even though the woman has more qualifications, works harder and longer hours and is better at the job than her husband, he gets paid more are is promoted more easily.
The kicker? He's won awards... but only for work she helped him with (advertising industry)
When people think a man did her work, suddenly it becomes more valuable lmao.
So basically, non-white male people have been burning themselves out producing amazing work and are barely getting by. Meanwhile white men, while yes they still work hard, they don't have to work as hard to get to the same level of return.
Even in day to day things you wouldn't think of like healthcare. Women find they need to work a lot harder to get a doctor to even diagnose them properly and not brush them aside.
So that's where the exasperated cry of "Fucking hell if I had half the luck of a mediocre white man" comes from.
It's not about white men being worse than everyone else, it's about how social structures favour them more. It's not saying mediocre POC women don't exist, rather that a mediocre man can survive where others will not simply because they are catered too in our racist, sexist society more than anyone else.