They're usually particularly interesting people, whose lives give curtain-twitchers a reason to get up every morning, thrill-seeking hedonists and kamikaze risk-takers who act first, then apply their surprisingly clear-sighted big brains to analysing the aftermath with admirable aplomb.

Robert Downey Jr, Russell Brand and Shaun Ryder come immediately to my mind but there are numerous examples of such folk in public life.

This week I was reminded of another one, recently caught up in yet another headline-grabbing and incomprehensibly rash bout of behaviour.

She might not be your first port of call if you're seeking marriage guidance, but the now infamously four-times married Sinead O' Connor (it's off again by the way) still talks a lot of sense when it comes to the thorny issues of happiness and success.

Speaking on Absolute Radio, O'Connor blasted the modern 'worship of fame' and its insidious effect on impressionable young people. She had a very good suggestion for the multitude of kids who leap hopefully onto the X Factor and Britain's Got Talent stage in the eager pursuit of wealth, power and global adoration every year.

Have a good look at the celebrities judging you, she said, their lives busy with 'emotional breakdowns and arguments and beating each other up.' Theirs, she advised, 'is a world you don't want to enter.'

If anyone knows this, it's O' Connor, who revealed last month she was seeking psychiatric help after becoming depressed because 'of what was done to my husband' in the wake of his marriage to a woman with the reputation of Sinead O'Connor's.

She says now that she will 'never again associate myself romantically with anyone', (in public at least), because she 'could not bear to see these things done again to someone I love'.

This last week has been littered with salutary tales of the pitfalls of fame. These aren't just inconveniences. For anyone remotely vulnerable to addiction - like Whitney Houston, the beautiful, talented god-child of Aretha Franklin, who began life among her tightknit, loving family with every advantage an aspiring singer could wish for - they can be fatal.

I've lost count now of the number of well-known people who have had death threats. Denise Welsh is the latest, but Kylie Minogue, Anton Ferdinand, Dom Joly, Louise Mensch and Imogen Thomas have all called in the police to deal with terrorisation in the last few months.

Meanwhile the Leveson Inquiry into media ethics rumbles on, exposing the journalistic intrusion into celebrities lives which made them prisoners in their homes and created such distrust within their own circles that friendships and family ties were destroyed forever.

So why does the quest for this lifestyle - which turns ordinary, functioning, semi-satisfied people into frightened, lonely, insecure, mentally unstable ruins - continue to motivate millions across the world?

Why does happiness have such low currency? A recent survey showed that a quarter of social media users regretted things they'd said online; a third had experiences of cyber-bullying.

Facebook is as close as most of us get to fame, and we already know how rotten the repercussions are if we do something daft on there. But we still don't seem to have joined the dots.

I don't say this often, but in this case people - listen to your mamma Sinead.