Hi Deirdre and welcome to the forum,
Definitely an element of truth in what you say about private labeling, however it takes more than just the brand name to make a product valuable. Consumers are pretty switched on these days, so if you are going to say ...... brand your own make up line, then why would anyone buy your product over and above another brand?
That's where the focus needs to be and then that comes down to marketing, to understanding the market, understanding what consumers are looking for in that genre, identifying those things and catering for them ... and then hitting the market at the correct price point to encourage sales.
Of course all that and then you're only at the start line, now you have to get the product marketed to generate the sales.
Lot more to it than just the product label itself.