there are two things i have a problem with when i hear why 30 is not the new 20:
1. the idea of having to settle down for life with the same partner is overrated. single parenting and shared parenting might be tough in some respects, but it's a lot easier in others. human "mate for life" is a religious imposition and not a normal natural tendency. in other words, you don't need to be worried about finding "the one" during the prime of your life.
2. i've become convinced that having kids is not something that needs to wait on one's career. a basic level of responsibility, yes, although that doesn't stop a hell of a lot of people from having kids they can't support. if you have kids early on, you can then start your career with maternity / paternity leave behind you. less pressure, no?
3. nobody has any clue what the future holds. the trick is to live each day like it's your last while still preparing for the long journey ahead. not every job you do needs to be serious, but any opportunity that you get to move towards a desired future should be given top priority.
most people spend their whole lives doing what they have to instead of what they want to. who defines success and failure? we're humans. we make up the rules as we go along.
you probably won't be able to figure out where you need to be until you've already stabilized yourself financially and found someone you might have kids with. that's irony!