There are two separate questions here: Is it stealing? Is it a victimless crime?
On the first point, I don't think there is much room for debate. Deliberately failing to scan items at a self-service checkout so you can leave without paying is theft. Whether it's a bottle of wine, washing pods, nappies or "the odd banana", the act itself is the same. People's circumstances may explain why they do it, but they don't change what it is.
On the second point, I think you are making a distinction that many people make, but it is a shaky one. It is true that stealing a child's bike feels more personal and emotionally harmful than stealing from a large supermarket chain. A specific individual loses something they own, and you can identify the victim immediately. However, that does not mean supermarket theft is victimless.
The cost doesn't simply disappear. Retailers lose stock, spend more on security, employ loss-prevention staff, install barriers and cameras, and write off losses. Those costs are ultimately absorbed through a combination of reduced profits, higher prices, lower staff hours, or less investment. No single customer can point to a 50p increase and say "that's because of @Alwaysthelastone stealing washing pods", but collectively retail theft has real consequences.
The bit that particularly stands out to me is the inclusion of wine. If someone said they stole baby formula because they literally could not feed their child, I would still say it was theft, but I could understand the desperation behind it. Wine is different. That is not about survival. It is far harder to frame that as anything other than wanting something and not wanting to pay for it.
I think you are softening your own behaviour by comparing it with something worse. "I'm not stealing bicycles", "I'm not burgling houses", "It's only a supermarket". But morality isn't usually judged solely against the worst thing somebody could have done. Most people would still regard repeatedly helping yourself to items from a shop as dishonest, even if there are more serious crimes.
Where I would perhaps differ from some people is that I think motive still matters. Someone shoplifting food because they haven't eaten for two days is not morally equivalent to someone regularly helping themselves to bottles of wine because they think Tesco can afford it. The act is still theft in both cases, but most people would view the first with sympathy and the second with much less. Stealing is stealing. Desperation can be a mitigating factor.
Supermarket theft is not truly victimless. Regularly taking non-essential items such as wine strikes me more as entitlement than necessity. What I find most revealing about your comments is not that you admit doing it, but that you appear to have convinced yourself that because the victim is a large company, it somehow no longer counts as real theft. That is the part of the argument I find hardest to accept.