1.7 million people in the US alone gets their whole blood system infected and 270,000 of them die - every single year. Your body can literally mistake your own cells and attack them - hundreds of autoimmune diseases ranging from diabetes to arthritis. Sometimes cells loose control and keep multiplying (cancer) actually about 8 a day for an average adult. You really surprised of infection not clearing up well? Endo success rate is 80-90% regardless and should be thankful that dentist explained that instead of just going in willy nilly, especially when the tip pf the root is melting away because of some eventful inflammation. Do yourself a favor and at least do some research, don't scream out your ignorance

Other than rant vs rant, as the other dentist mentioned removal and false tooth + save up for implant or just live with false tooth

Is that a decay in the tooth next door? Appears to be in the nerve and since the end of roots are quite close to each other, one may make the other worse and vice versa. To be sure, ask for a cold test or vitality test of the front teeth next time you go