Sadly that really isn't true. Never has been. Never will be.
It's purely a way for the wealthy to justify themselves, a simultaneous pat on the back and a way of turning their back on the poor. "Oh they didn't work hard enough, not like me, I worked hard, I took risks". Truth is some minimum-wage drone in an Amazon warehouse works harder than Jeff Bezos ever did. Same with care home staff. And so on and so forth.
It's easy to "take risks" and "work hard" when your family is minted.
Sadly pointing all this out is too often labelled as "jealousy".
I also think this explains the rise of mental health problems in younger people. The truth is you can't be who you want to be if you try hard enough, hard work and risk-taking isn't the solution, most people will achieve comfortable nediocrity as a absolute best. Sadly we're not taught this, we're taught that people like Elon Musk- who came from a fabulously wealthy family- are "self made".
I suppose there are different types of hard work. We all have different traits, skillsets and personalities. and someone who can be a great physical worker might not possess the same traits to be a strategic thinker ot a data whizz, or a logstical expert which at times, may be just as important. To "work hard" is quite subjective; does being on your feet for 8 hours in a warehouse require more "work" than trying (as an example) to develop a budget, a strategy and persuade people of your business vision? Most people will think physical work is "harder" but it isn't as black and white.
Society has - for better or for worse - decided that some skills are worth more money than others. For instance I could never be a nurse or a carer, but feel I am very suited to my current field. And vice versa, there are lots of people who would really struggle in my current field. I am paid more than the average nurse - I don't necessarily think that right as they almost certainly play an more important role in society that I do. However the barriers to entry for being a nurse a far less; most people could qualify to do it. Same with the warehouse worker; almost anyone
could do it. General economics plays a role, which is somewhat perverse but understandable when you think about it.
I do think you are correct that people who are "self-made" are anything but; you go back far enough and you actually see that decades ago they were given a "start up loan" by their family that helped them grow the business at a critical point that other people may simply have never had the option for. And there's definitely some luck involved. People like Musk & Bezos should be more magnaminous about their success.