You must be confused between
altcoin mining and
bitcoin mining, though that's fairly easy to distinguish based on what hardware/machine the miners are using.
• Altcoin mining generally uses GPUs since they are much more efficient in hashing out certain complex algorithms that altcoins used compared to ASICs which are programmed to solve
problems for bitcoin.
• Bitcoin mining utilizes ASICs (such as Antminer S9s and whatnot) since they are more faster and efficient into solving SHA-256 based coins since it is programmed to do just that.
Most people who aren't familiar with how mining works often mix up the two, though again it is easy to differentiate one from another, and that is mainly on what hardware are the miners using. You still can mine bitcoin with the use of GPUs though through a dire effort; your GPU will only generate massive heat and use up a lot of power without you profiting or worse, end up with a faulty/dead card.
Also, if you have the time, you can read out
this one in order to expand your knowledge regarding the topic you need help with.
EDIT: Wording and have sent the post too fast when it isn't finished, lol