Working hard is absolutely ONE COMPONENT of financial success. Without hard work, very few people will be successful. Paris Hilton, I suppose is the exception to that rule -- and really, I suppose we could argue that her family is rich, but she herself isn't really responsible for her financial success. Even if you consider people who discover oil on their family land to be financially successful, hard work was still involved. Someone (maybe the newly rich person, maybe an ancestor) bought that land, maintained it, paid taxes on it.
However, other factors come into play too:
Natural talents, ability, and intelligence. For example, I know a couple kids at school who work SO HARD every single day, but -- for one reason or another -- it just doesn't come together for them. One I'm thinking of is what used to be termed "educatibly mentally handicapped". She can do literally everything in her power, and it still won't be near what my own daughter could do with immense ease. On the other hand, look at someone like Michael Jordan. He was born with natural talent. Someone else could put in just as many hours on the court and still not equal Michael Jordan's accomplishments.
Choice of profession. Some jobs pay more than others. If you choose to be a social worker, you will never earn CEO pay no matter how hard you work.
Thrift. How you spend what you have matters tremendously. We all know people who earn about the same salary we do, yet they're either doing much, much better financially . . . or they're doing much, much worse. Anyone can manage what money they have well -- if they work at it -- so that really could fall under the hard work category.
And finally luck. Being born with a healthy body, with parents who are supportive of education, in an area where jobs are readily available, in a time period where health care is available and no wars are going on -- all these things certainly give a person a leg up. And, of course, the opposite could be true too. A person born without those benefits could still be successful, but he'd have to work harder than a person to whom those things came freely.
So, I'd say that hard work is absolutely NECESSARY for financial success. Without it, financial failure is almost a sure thing, BUT it isn't enough in and of itself.
I totally agree with much of what you've wrote, except for:
1.) Paris Hilton was lucky enough to be born into a rich family. However, I believe she has worked very very hard to sell herself to make more money. She could easily have been just another heiress that we could not name, but she deliberately put herself out there (albeit unsuccessfully) with her TV show, movies, music album, perfume line, etc. While it looks to many that she is famous for nothing, she has not just been sitting on her butt eating bon bons.
2.) Was Michael Jordan born with natural talent? He was cut from his high school basketball team and that spurred him to work harder and practice harder until he succeeded. Few people are born with natural talent. It just looks that way because we don't see what it takes to make that happen. For example, tennis players like the Williams sisters or Andre Agassi often have tyrannical tennis dads that drilled them since they were small children. Even Mozart's dad was a composer and worked him hard when he was a child.
I'll just add to your notes:
1.) Luck has a lot to do with success. If you read Malcolm Gladwell's book "Outliers" he talks about various successful people and how they got there. Examples include Bill Gates, who lucked out with having access to computers (before anybody else) and the time and motivation to put in his 10,000 hours of practice. Had he been born 10 years earlier, he would have already been saddled with a wife and family working for IBM. Had he been born 10 years later, he would have been too late. One of Malcolm Gladwell's keys to success is that you have to put in at least 10,000 hours of practice into something before you can be a champion (no matter what it is). Nobody has skated by on "natural talent".
2.) Choice of profession--yes! Some of the lowest paying jobs require you to work the hardest. Why don't they pay better? Because of supply and demand. If there are plenty of people willing to do your job for less, why would the business pay YOU? The highest paying jobs are ones that very few people are qualified to do (this includes being an actor, athlete, musician--which people often feel are overpaid). High paying jobs also often require sacrifice of time or education (think of all those men who never see their wives or children and miss all the important milestones of their lives).
3.) Thrift: totally agree. One trend I've noticed with a lot of the unemployment/foreclosure stories that are always circulating in the media is the common theme: was making good money, bought too much house, lost job or had medical bills, lost house. While I feel bad for them, I think they were unwise and should have bought a smaller house, saved a large(r) emergency fund, and planned for bad times. It seems like times were good for so long that people never planned for a rainy day and were caught unprepared.