IT is the scenario everyone dreams of: circling the numbers one by one as the balls roll out of Camelot's high-tech tombola machine until you realise that all the numbers on your ticket match the line-up on your television screen.

In seconds, your life has been changed forever.

That was the experience for retired Largs couple, Colin and Chris Weir, when they checked their EuroMillions ticket on Tuesday night to discover that one of their five lucky dip lines had made them the winners of Europe’s biggest ever lottery jackpot, in excess of £161.5 million.

Married for 30 years with two grown-up children, the down-to-earth pair spoke on Friday of the “adrenaline rush” of the win and their plans to invest in properties for their son and daughter, a call centre worker and photography student respectively. Overseas holidays in the Far East and Australia and trips to art galleries in Paris and Russia are also on the cards.

But what happens when the initial euphoria dies down? Joining the exclusive club of lottery millionaires is the stuff of fantasy for most of us, but it is a club full of tales of loneliness, despair, and tragedy almost as often as joy as many winners have struggled to cope with the psychological pressures of much smaller jackpots.

In January 2010, Scotland’s youngest jackpot winner was found dead at his home in Dumfries and Galloway, 13 years after scooping his £1.9 million prize. Stuart Donnelly died alone aged 29 in the cottage he had transformed into a millionaire’s paradise, with a full-size snooker table among other luxuries.

A 17-year-old trainee pharmacist when he won the jackpot, Donnelly lavished his fortune on his family, foreign holidays and good causes, but was left grief-stricken when his father, Danny, suffered a fatal heart attack.

Donnelly became a virtual recluse, listing his interests on his Bebo profile shortly before his death – from natural causes – as: “Sleeping, watching TV, listening to music, surfing the net. Basically, anything that involves not leaving the house.”

And former shipyard worker, John Currie, from Govan in Glasgow, died in April this year, aged 66, months after describing how his own £6.5m jackpot win had “ruined his life”.

The father-of-four – a heavy drinker already suffering liver disease and diabetes – described how splashing out on an upmarket bungalow in Bearsden following his 2004 windfall had left him lonely and isolated, and that after giving millions away to his family, taking lavish holidays with friends and investing £1.5m in shares he had been left virtually penniless.

Since the game was launched in November 1994, 222 lottery millionaires have been created in Scotland – but what, if anything, separates a good winner from a bad one?

According to Glasgow University psychologist Professor Paddy O’Donnell, a lot depends on a person’s natural “happiness thermometer”.

He says: “The psychological research shows that people’s level of happiness tends to be individually fixed. Some people are a bit less happy than others, some people are a bit more happy than others. When we get a very good or a very bad event, then that tends to affect us for a short time. But we tend to regress to our preferred level after a few weeks… Having a lot of money initially will make you feel good, but it wears off.”

The real psychological pressures come after that initial phase, says O’Donnell. “What people think is, ‘I’d clear my debts, I would add that bedroom to the house, I’d give my sister £10,000’. They think of winning the lottery as a small improvement to their present life.

“But having the actual £30m or whatever then leads you into all these problems of emotional distance, fitting in with a new group, and not knowing what to do with the rest of your life because what do you work at?

“What do you do with family and friends – do you give them money? OK, that makes you feel less guilty and expresses your affection for them. But how do they handle the relationship with you because they are now, according to the psychological principle, in your debt?”

Many jackpot winners also contend with feelings of guilt over their “unearned” fortune and isolation if they uproot to a new neighbourhood.

The Weirs will need their wits about them to navigate the demands, expectations, guilt and public scrutiny. The odds may have been about one in 116 million, but winning was the easy part.