It's easy to say all these things, but the ground reality is that we don't have much time on our hands, given the high probability of a war breaking out in the next few months or years.
Our squadron strength is depleting rapidly, with many airplanes already at the end of their operational lives.
The last thing we want is to derail the LCA Mk1A, Mk2, AMCA, Naval Twin Fighter, and even future Rafale procurement just for the sake of the Su-57. Moreover, given the mercurial nature of Trump, he may also target the Indian economy, which would be highly damaging.
Unlike Pakistan, which shows little concern for the well-being of its citizens, we cannot afford a survival economy. A minimum 6% growth rate is essential for the foreseeable future.
And in the end,If the Su-57 turns out to be a white elephant(which most probably it is), we would be staring at a doomsday scenario.