Most cold calling is based on a call list that is purchased. Bit like when your email starts to receive spam - your email (or phone) details have been sold on.
Depending on the list it may well have age category details as well as.
The other possibility is that they aren't specifically targeting an age bracket, just that when the scammer realises they have contacted an older person they change their tack and become more pushy.
It most likely is the 2nd possibility I would suggest.
Time of day the calls are received could be a factor. Maybe there are numerous calls made by an autodialler. If no response or answerphone or commercial line, proceed to next one.
Most of ours are between 12.30 and 2.30.
I have a simple method for avoiding spam/scam phone calls - if I do not recognise the displayed number, I do not answer.
If the caller genuinely needs to contact me, they can leave a message on the answerphone.
Based on my understanding, these kind of calls are based on calling lists as alluded to by @dmmsta above being sold on from third parties. The information on these list is compiled from cold called ‘life style’ surveys, or you are even stopped in the street, where they elicit enough information from you to put you into a target group.
That is why I never complete these, unless I know the source to be genuine. Even callers coming to the door I treat them the same telling them I will never give information or money at the door, if I want to make a donation I will do it via their web site.
A few years ago my name and phone number was on one of the "Sucker Lists" circulating among the criminal boiler rooms whose workers would phone me out of the blue to attempt to sell me a duff investment. Judging by some of the opening lines someone stole a list of Pilkington Glass shareholders a few years previously. I used to have a few hundred of those shares for a couple of years..
Among the "opportunities" offered to me: Carbon Credits, Coloured diamonds, real estate in Brazil, shares in Nanotechnology companies, fine wine investments, rare stamps, shares in overseas drug development companies, gold bullion. I always answered their calls and listened diligently listened to their proposals. I'd tell them, after working in the "City", I was a careful investor and what they'd proposed sounded risky despite the high returns. I'd let them send me glossy brochures and prospective documents. But,... I was never quite ready to make a decision. I needed time to think about releasing money from my other investments, or I was about to travel to Switzerland/Bermuda etc., These people would have London or International Offices, which you could never quite succeed in visiting. I once took the trouble to pass a dossier to the City of London police, but they were not really interested.
My objective? To get these criminals to waste as much time as possible talking to me and sending letters. That way they'd have less time to approach people who were more gullible and would accept their polished slick presentations.
If someone calls out of the blue offering an opportunity, assume it is a con.
How about turning the tables on them and doing the Nigerian lottery thing of saying you need them to give you a few thousand pounds so you can release the money required to invest in their proposal?