Can microblading not work for certain people?

I'm interested in microblading as want my eyebrows to look thicker, especially at the tail ends. Been doing some research and some people have found that even after their touch up, most of the colour goes. Also, I read from one place that does this treatment, that some people's skin just doesn't retain the product/colour. I don't want to spend money and end up with no improvement or patchy eyebrows. Could anyone help me with these concerns? Thank you.