"Ridiculous" means laughable, laughable because it is obviously and hilariously not good enough.
However in English "a ridiculous amount of money" is "a ridiculously large amount of money". In general it seems that "a ridiculous amount" is always "a ridiculously large amount":
- «That's an absolutely ridiculous price for that sweater»
- «Don't be ridiculous! You can't pay £50 for a T-shirt!» «They ate and drank a ridiculous amount» «The meal was ridiculously expensive»
- «Hedge fund giant David Tepper made a ridiculous amount of money in 2013»
- «Beyoncé has sold a ridiculous amount of albums since Friday»
- «GTA role offered to Alec Baldwin for “a ridiculous amount of money”. Alec Baldwin turned down an “incomprehensible amount” of money»
- «… it's a ridiculous amount of pain for such a light touch …»
- «5 year old genius knows a ridiculous amount of geography, turns down a Sony tablet»
- «Our teacher gave us a ridiculous amount of homework tonight», nº 24
- «She had spent a ridiculous amount of money buying this apartment, free and clear, for cash, the way other people bought sweaters. She had spent a ridiculous amount of money buying her little tangerine orange Mercedes sports car, also for cash»
- «I did love that piece, Bernard, but you were right when you said that $1,688,000 was a ridiculous amount of money to pay for a piece of furniture. So I decided to auction it off in the hope of obtaining an equally ridiculous amount of money that I could use for a better purpose», page 199
In my opinion this is an antiphrasis exactly as "terrific", "tremendous", "awful", "sick", "bad", "wicked", etc., when used with a positive connotation.
When an antiphrasis becomes popular, a proper semantic change occurs, in these cases it would be called an amelioration. But it is important to stress how a semantic change of this type is often originated from an antiphrasis.
If you agree with this premise, my question is: when and how was the meaning of the adjective "ridiculous" inverted from "obviously and hilariously not good" to "absurdly great" when referred to an amount of money?
Otherwise, can you explain why you do not agree with the premise?