Yeah obviously it's a different story with Murray given his wealth. But in general for us regular folk tennis is too risky and too expensive a career path to encourage your kid to follow. It's fiercely difficult just to break even in career earnings. It's much safer to stay in education and gain qualifications for as long as possible, and then get a 'normal' job.
With a team sport it's a completely different kettle of fish. Your kid can still have more of a settled home lifestyle as they don't have to travel anywhere near as much or as far, expenses are lower and clubs subsidise a lot of those expenses anyway. Plus they have team-mates to share the mental burden with and socialise with.
Tennis is a sport where challenger level players are much worse off financially now, than they were 20 years ago in 1996. Players' travel, coaching, equipment, nutrition and accommodation (not subsidised at challenger level) expenses have all increased in that time with inflation, while challenger level prize money has barely increased at all. Many people are understandably crunching the numbers and realising that it's just not worth the time, money and sacrifice .