The $16M net wealth figure also came from Forbes, so they would have factored in his endorsement earnings.
Endorsements tend to fluctuate significantly based on performance so it is a massive assumption to say he has earned $12M a year every year since 2014. You are also making some massive assumptions about the amount of income he has converted into net wealth. Do you save 50% of your before-tax earnings?
You also need to bear in mind he has also had a very expensive divorce in that period that would have taken a significant chunk of his assets, not to mention ongoing costs in terms of spousal maintenance and child support.
Can you please link the Forbes list that shows Wawrinka with only at $16 million net worth today?
I looked deeper into the public numbers. Wawrinka was a junior French Open champion and has been a pro for over 18 seasons. Due to junior accomplishments and early pro success, he has been popular in Europe and earned decent endorsement money off the court for most of that time. Prior to getting married, he had won about $3.5 million in prize money and doubled that with sponsorships with Head and Sergio Tachini for around $7 to $8 million in earnings from 2002 to 2009.
Wawrinka was married in December 2009 and got divorced in April 2015. According to Swiss law, he would retain anything he owned prior to marriage and would only owe his wife half of what he earned during the time they were married unless there was a prenuptual agreement (which I would bet he had unless he gets terrible financial advice from his management). He would have to pay a reasonable amount of support for his daughter, but alimony would not be usual in Switzerland unless his exwife was disabled and unable to work (which is not the case since she is a former model and current television presentor). During the timeframe he was married, Wawrinka won the Australian Open and several smaller tournaments to pocket about $11,500,000. In 2014, he reportedly signed a 4 year/$20 million contract with Yonex, replacing his former deal with Head. Depending on how his deals were structured, he likely had at least as much endorsement and appearance money as he made in prize money, which would have grossed him about $23 million total, before taxes. If you have details on their divorce settlement, please share. However, it's likely his wife got less than $10 million at best before he was clear.
After the divorce, Wawrinka really started making big bucks. Forbes has him as making $47.5 million from mid-2015 through 2017, where he won the French and US Opens and was one of the top 10 highest paid players in the world during that time. Since the end of 2017, Stan has won another $3 million in prize money and raked in endorsements of about $10 million.
Totals for his career are somewhere around $90 million. If half of that was spent in taxes and playing expenses, that means he's netted about $45 million. If he had to give his exwife $10 million (probably not), that leaves him with $35 million. Net worth is not just what you've saved in cash, but the accumulation of all your property and investments. So if he has banked $35 to $45 million in his career and purchased a house, cars, and a boat, and stuffed money into long term investments... how is his net worth only $16 million? Did he just go light $20 million on fire? Did his house become worthless? Did his manager run away with his retirement cash? I say his net worth is in the $30 to $35 million range at least, especially if he has made good investments.