A science career looks easy on paper but in reality it is a pyramid scheme. Every year each university trains thousands of students. Many of them reach the Masters level, but most are smart and jump back into the real world. This is the true starting point of a science career since after this point there is no returning back to the civil word with your sanity intact.
Master students are often the work ponies of labs all around the world. They don't tend to hang around too long so they are extremely well suited for flirting with. Especially if they are from the opposite sex.
Sometimes the master student gets stuck and starts a PhD. The base of the pyramid is thinned out. The PhD student is the true work horse of every lab. They are cheap, plentiful and easily malleable. Luckily for most labs there is an increase in funding each year for more and more PhD students. That's because it looks good on paper to train high quality PhD students.
The PhD will take 3 to 10 years of your life, or even eternity. After getting your PhD you are finally a qualified independent researcher. Most people can't handle this depressing thought ans bail out. The previous 3 to 10 years of torture is still to firmly in their memory. Many groupleaders proclaim it is difficult to get good post docs.
On paper that sounds good for the people that remained in the game. Unfortunately there are hardly any longterm positions. Any idiot can get a position as a postdoctoral researcher for 3 years. Sometimes they get another 3 years in another lab. And sometimes they add another shift in another lab. Still no permanent positions.
The very lucky ones apply for a groupleader position Unfortunately these are nowadays also not permanent positions. Usually you get 5 years to prove yourself on paper. After that it game over, or maybe a lecture position.