The trouble is that no decent person would want to further impoverish pensioners who have no money. But pension credit does make recipients better off than those on the margins - not the actual credit, but the gateway benefits that qualifying brings - Housing Benefit, free social care, help with council tax etc.
I don't think that people who are in this position (earning little, but working hard) are listened to at all, and this oversight is responsible for a lot of the resentment and division we see in current society. Very broadly, the left accuse them of being uncaring and (ironically) elitist, and the right see them as collateral damage in the quest for a free-market economy.
It is not unreasonable to expect to see a lifetime of work leave you better off than if you had lived a life of not working. Only the fortunate work for the fun of it - most of us do it because we get paid. If we can get the same money for not working, why bother? The problem is that as things stand there is a choice between penalising those with no money, which is (a) pointless, as they have nothing to take away, so penalties would have to involve cutting benefits, leaving them to their own devices and letting them rot, and (b) somehow forcing people to work and fetch for themselves. Jeremy Hunt talked on LK this morning about using a stick rather than a carrot on the unwaged, which sounds very like a combination of (a) and (b). Unsurprisingly, he didn't comment on the potentially exploitative nature of compelling people to work for benefits, on how the 'stick' would work in practice, or on how he would separate the deserving and undeserving poor.
Meanwhile, people on minimum wage or just above are getting up early, working long shifts that might mean seeing less of their children than they would like, spending their lives doing unrewarding jobs, and seeing their neighbours not working but having similar amounts of money coming in. To add insult to injury, there are all sorts of concessions for people on benefits - free courses, entry to visitor attractions etc, which might be out of reach for those in work. Of course that is galling for low-paid workers. Those who have worked in rewarding careers and earned enough to save for a comfortable retirement are right to want to see their work rewarded too, but I do get tired of hearing how mean-spirited it is of people to resent those on benefits getting free access to things others have to pay for. It's a privileged perspective.
The only solution I can think of is to raise the minimum wage so that all workers are better off than those who don't work. If we all paid higher taxes but means-tested benefits were replaced with universal ones, so that everyone got child benefit, decent pensions etc at different points in our lives, there might be an incentive for people to save, invest in occupational pensions, work towards promotion etc (the things the person in the OP is accused of not doing), in order to see the benefit of doing so. As things are, there is only a real incentive if you know you can afford to save enough to outstrip the financial benefits of not bothering.