Why does TB treatment have to be completed even after you feel fine?

Because feeling better happens weeks before the bacteria are cleared. TB treatment typically runs six months precisely because the slower-dividing bacteria survive the early phase, and stopping when symptoms lift leaves exactly those behind. That is the main route to drug-resistant TB, which is far harder and more expensive to treat and takes much longer. India carries a large share of the global drug-resistant burden, and incomplete courses are a major driver. If side effects are the reason you want to stop, tell your doctor — the regimen can often be adjusted rather than abandoned.