Fair enough, TMH, and thanks for that - my knowledge of precolonial Indian history is admittedly extremely sketchy. But my point was, to attempt to draw conclusions on the basis of before-and-after GDP percentage is therefore extremely disingenuous. I know it wasn't you, but someone else said something to the effect of "India was the richest country in the world, with 25% of the world's GDP, when the British, who had 1% of GDP, came... and after a few years it was the inverse" - the logical implication being that the British literally showed up, stole your stuff, put it in their own country, and became the richest country in the world through pure self-aggrandization. I have no doubt that statistic legitimately exists somewhere, but I'm sure you can see why calculating that statistic on the basis of the very first days of EIC rule would be extremely misleading. The more pertinent question is what the relative percentages of global GDP were around the time of Clive of India - and even I know that most certainly was not 25% India and 1% UK.
In other words, the cause and the effect are a little bit mixed up here, I think? Were you the richest country in the world before the British began to call the shots, or had the rot set in - as you say, Mughal invasions and what not - prior to that, allowing the British (whose military and economic power, thanks to the Industrial Revolution, was most definitely not 1% of global GDP) the opportunity to call the shots in the first place? Because as I understand it, the former is being argued in this thread at least by some (not necessarily you), when it's an extremely counter-intuitive argument to say the least.