Parents get crazy advice. Have you ever been told that “Some babies just don’t sleep“?
That’s so crazy! Babies desperately need sleep and may need special help learning sleep skills. I helped a family of 6 kids not sleeping and their doctor told their mom that her kids just don’t sleep. –As if it was natural and normal!  I had her kids sleeping in about 6 weeks.
Have you ever been told “Your baby is playing you.”?  “So let him cry it out.”
Manipulation is far too complex an emotion for a baby. (That’s more of a teenager thing.)
It’s just ’cause and effect’. Your baby has figured out that when he does this, you do that. So gently change your response and they will change their behavior.  If your baby cries that way and you come running, they have learned to cry that way to get you to come running.  It’s not a bad thing at all.  At night, starting with bedtime, gently change how you respond depending on the situation to get a different behavior from your child.
It’s not rocket science. It’s behavioral science.  It’s always great to be there for your child but you don’t have to give them everything they want.
My kids want chocolate for breakfast. Yeah, I don’t think so.  But I am definitely going to be giving them breakfast, just not the one they think they want.  Except maybe on their birthday.