Is weed actually bad if used responsibly?

Ok so im wondering. Last year i went hard on the pot. and i became more stupid just cuz i had so much access to it i was too busy thinking of when im gonna get high next caused me to fail. i then quit for 3 months got my grades to a 50-60 (a pass) and well went on the pot again. I did it responsibly. i had 2-3 moments where i greened out but besides that. I control my high. and im not a total stoner everyday. my marks shrunk like 2% down but i think its just cuz. Ive passed my final exams and passed gr.8 but im wondering. is it actually that bad? of course its bad for your lungs i mean its smoke but anything else??