This question can be approached from many different angles, but I could theorize from one of them.
(Warning: wall of text - TLDR version at the end of this post)
The most important and non-renewable thing in this world is time (and health to a certain degree, but I digress). No matter how rich or intelligent you are, we as human beings have finite time in this world to do whatever we wish to do. When you have limited time yet a lot of milestones to achieve in life, you naturally want the shortest way to get to all of them.
Enter money, the tool to get most of the things you ever want in life quickly: education, career, house, marriage, worldly pleasure - things that are theoretically achievable without the use of money yet not much so in practice. Hence, everyone needs money; and everyone mostly gets them by working.
Now, there is a reason why people say “work smart, not hard”. A lot of people think this is something only Millennials and/or Generation Z champion, but it only feels so because the impact of not working smart is more significantly felt after the 90’s due to economic globalization.
Cross-border business activities bring opportunities never before seen by people from countries who have lower economic welfare - yet that also means competition is very fierce nowadays, which translates to lower salary/wage being offered by people/companies who merely choose the lowest bid to maximize profits.
If we use Fiverr as a live example, you can understand the effect of uneven supply and demand by the number of new (and even some of the more seasoned) sellers offering their gigs for cheap.
I’m pretty sure nobody wants to put all their effort and hard work to be paid a pittance - especially those who have real skills and experience. So what is the workaround? You work smart.
Maybe you put $5 for your basic gig but limit the value of what your buyers will get. You want the full value? Buy the most expensive gig. Or perhaps you have a template to refer to for your gig so that it doesn’t take a lot of your time and you can work on your gig more efficiently and get more jobs done. Last, we have the highly frowned-upon, unscrupulous sellers who steal or resell or lie about their competency to get a job. These are all working “smart”. And working “smart” makes it “easier” to get money.
However, it is worth noting that if one decided to use unlawful ways to get money quickly, he/she would always get caught eventually - whether reported by fellow sellers who found out about their unethical ways, or by buyers who had a bad experience working with them, or even by the Fiverr staff who stumbled upon them once upon a time.
TLDR: Death comes to all humans, but we want to get lots of good stuff before we perish - and the good stuff can be ours via money. Money is received mostly from jobs, but jobs nowadays are hard to come by because of global competition. To not go mad with being paid peanuts for the rest of our lives, we work smart by doing stuff to minimize our effort and justify the pay. The end.