I'd be willing to correct you on that, personally. I am of the opinion that via DIY I can learn and create the optimal flavors FOR ME, in a way that a commercial outfit cannot. In fact, it is very frequent nowadays for me to encounter eliquids that are over flavored (to my palate) over sweetened (to my palate) and often kind of harsh or chemical tasting. Not every last one, but many.
Now that my tastebuds have grown back I can tailor my juices to what I enjoy, and what I find pleasant, over time. I started out very simply (to learn flavors and steeping times) and I've read a lot of recipes, flavor reviews and etc. As I learned flavoring "building blocks" so to speak, I have had more and more success creating recipes tailored exactly as I like, and really ideal-- for me.
Usually if I'm making other people flavors coming from commercial juice, well I know that I will need to over flavor and over sweeten (for me) but usually have them pick a couple dominant flavors, send them away, and give them something I think they will enjoy. I've been fairly successful at that by simply asking what types of juices and flavors appeal to them. Most folks coming straight from commercial juices aren't going to enjoy my "personal" creations, which are far more nuanced (hard to do with say, 20% total flavoring) and a lot more creative. I'm happy to say that the only recipes I've ever used were my own creations.
It takes time to develop skill, certainly, and I approached it just like cooking-- Learn your ingredients and flavors, and develop progressively more complicated things, amending if needed. I learned to cook that way because if I'm making something and missing an ingredient, it's easier to know what "things" work well with what, and have the ability to do substitutions or experiments with ingredients.
Really though, although it takes time, and effort, I think to say that at home DIY must somehow be "worse" than commercial flavorings? Well the majority of commercial outfits are using the EXACT same things as I am, just in larger amounts. Everyone uses similar flavors, etc. There's no reason at all to think that you couldn't make a perfectly enjoyable set of juices for yourself, and that they won't be "as good as" commercial flavors.
How good you get depends in part on some natural aptitude, as well as some desire to learn about and research stuff. But, I'd imagine there are many DIYrs out there who are more creative, and spend more time creating their own elquids and do as well as or better than commercial outfits.
I'd kind of wipe that idea out of your mind. My initial offerings were certainly not better than some commercial juices. Some specialty juices such as NET or WTA, well, I tend to leave those to the professionals, but otherwise, I've been more than pleased with DIY and you certainly can be, too.
I'm sure you'll make your share of "vomitous' juices, we all do that. I kind of expect 1 out of the 11 flavors I make on "DIY" day to suck, and am often pleasantly surprised when I like ALL of them. I've been at it awhile, and my skills have steadily improved.
But no reason to think you can't be as "good as or better" than a commercial outfit. You have the exact same set of ingredients to be purchased as a commercial outfit, just in less volume. You can be as much of a success as you put your mind to. Etc.
Anna