It only makes you poorer if you displace a more productive use of your time
If the time required to make my own toothpaste meant I had less overtime at the pin factory, or less time doing something I considered more enjoyable like Facebitch, then it makes me poorer. But if it displaced time spent zoning out to reruns and infomercial on late night TV, at the very least I'm richer by $3 or whatever a tube of toothpaste would cost me.
I tend to compare more with doing things for myself that offer a bit more savings. For instance, while I'm far from as handy as others I can do simple plumbing or car repairs myself. If it takes me four hours to fix something a plumber or auto mechanic might take an hour to do, I'm saving let's say $75.
Obviously giving up four hours of work for that would be a terrible idea, as I'd make much more than $75, but if I were on minimum wage it would make sense to take time off work to do my own repairs (though not as much sense as doing it in my spare time!) What's the value of four hours of my spare time? That's hard to put a figure on, but I derive some personal satisfaction from accomplishing these things on my own (some, I'll admit, due to the fact I'm saving $75)
Doing my own repairs certainly isn't efficient for the economy as a whole, as I'm much more valuable doing what I'm best at, rather than doing something others are best at and I have to struggle a bit to accomplish and may fail attempting. As I'm unwilling to sell the market all of my waking hours, the value of my time to the overall economy beyond the 40 hours a week I choose to sell to it is far less. If I post to the Reg, the value of my time to the economy is zero, but it has value to me or I wouldn't do it.
One can't underestimate the value of personal satisfaction you get from doing something for yourself. I would get no satisfaction out of making my own toothpaste, but others get no satisfaction from fixing a leaky faucet and are happy to pay a plumber to do it for them. Sometimes things people simply enjoy doing turn into careers, like those who had a hobby making beer and now run craft breweries.