It really isn't unattainable. I could do it easily, but I would have to eat a lot of shitty food. Seriously, I wish I could take this bet. I have done it before, not always 7500 cals per day,but a lot. I put on almost 25 lbs in 5 months....I didn't feel so great, didn't look so great, but my strength was at its highest.
When I was doing it, it seriously felt like a full time job. I had to set my watch for every two hours and eat...fuck that shit....ain't doing it again! BUT it can be done!