You can't buy a competitor if he don't want to be sold. Neither can you threat somebody with violence if the government does its job. I don't even comprehend how the absence of interventionism presume allowance of such violent measures. Don't confuse violence with "non-competitive practices". The latter are seldom harmful, or at the very least much less harmful than those leveraged by the allowance of interventions.

So they've provided a worse service? I'm fine with it, if it means lower prices.

Of course they had a choice. And not only "to sell or become worthless", but also invent or innovate, as Amazon did, when it swallowed a huge chunk of Walmart's pie.

I don't know if Amazon is good or bad, neither myself nor anybody around ever used it, but if its service would not be good enough, any competitor could easily use it to conquer the market (as Amazon itself did), until Amazon would protect itself via regulatory capture.