What should we think about wrong notes, or mistakes generally? Whether we like it or not, they happen frequently when learning the piano, and are an essential part of learning - Just like a child learning to ride a bike. By falling off a few times, they learn how to 'not fall off'!
And there's that well-known saying — 'An expert is a person who has made all the mistakes that can be made ...'
I want to stress that it is essential you allow yourself to make mistakes, and not feel bad about them. There are always reasons why they happen. You just need to try to figure out what is causing them. It might be having difficulty reading the music, technique that's not up to scratch, awkward fingering, being distracted, or even just feeling tired or sick. There are many factors that may be at work.
When practising, always be listening carefully to your playing so that your mind will be attentive to the details of your playing. If you are in the early stages of learning, you might not immediately be able to interpret, or address, what's going wrong, but rather you might have a general feeling that there is 'something not quite right'. In these cases it's important not to just go blindly over and over the thing that is bothering you if you don't understand how to fix it. Just make a note of it and make sure you ask your teacher next lesson. It's much better now to move on to something that you do know how to work on.
A really good way to progress is to work on small snippets of music at a time. This allows you to concentrate on specifics and reduces the likelihood that inaccuracies will go unnoticed. And a very common mistake is to just play the piece from beginning to end, hoping to get it right. It's likely you will just have a dissatisfied feeling that it 'wasn't very good', without really knowing exactly why. The only way to 'get it right' is to have addressed all the issues specifically.
A further strategy is to work on sections at the end of the piece first, rather than always working from the early sections and moving through. This way you will better cover all the issues in the piece, rather than getting 'stuck' on the earlier parts.
Most people would have experienced the frustration of continually making the same mistake again and again. Of course when we are practising during the week, mistakes happen. That's a given! But they are even more likely when a person learns from the internet, without having a real teacher to see what they are actually doing. The person may be going about things in the wrong way for a long period, and never know it, and then when they finally decide to see a teacher, there has been a lot of damage done. By this time, poor technique has become very 'ingrained' and difficult to correct. This can be a major drawback of learning to play piano solely from the internet. Of course it's possible to learn aspects of piano playing on-line, but there needs to be significant input from a real teacher for learning to progress properly.
So to conclude, we can say that making mistakes or playing wrong notes is certainly not 'bad'. If we understand their causes and work on solutions, we will become much better pianists.
And I've mentioned some ways to approach your practice time to allow you to get 'better value' from it, and ultimately more satisfying results.