What's your opinion on Waist Trainers

So I just bought my first waist trainer I have a really hard problem with my muffin top. I'm so self conscious of it I use to wear tight spanks every day to school. I'm 17 and a senior. I have had all of these people tell me how they are bad for you when honestly I don't really think it's all that bad. Makes me sweat but you're only suppose to wear it for a set period of time like 4-8 hours. So I don't see how it could be so terrible? Thoughts..? Also what are some exercises that actually help? I do Russian twists and a ton of ab workouts but nothing seems to be helping it go away....?

My waist without it on is 29"

with it on::

first hook I'm 28"

Second hook I'm 27 1/2

Third hook which is very tight I'm a little under 27"