Would you want to live in your bathroom for the rest of your life? Don't plan on getting an animal and treating it badly. It won't be alive in 5-10 years for you to upgrade it, because a even a 4 foot long fish makes way more waste than your tank or filtration will be able to handle. You can buy one, it will live a shortened, miserable live, and then it will die. If that's what makes you happy, then why not? But you're not going to get people on this site to tell you what you want to hear. Most of us are pretty disgusted with people who are asking the same questions you're asking.