That's absolutely not true. Here's
what we know about both games sales number:
-According to Famitsu's sales tracker, Game & Wario sold 80k during its entire liftetime. Gold sold 96k in its debut month (making it the best-selling new release of August) and it is still hanging juuuuust outside the top 20.
-In the UK, Game & Wario didn't chat at all in the top 40. Gold did (albeilt only at #38 before dropping off the charts entirely)
-In the US, Game & Wario didn,t chart anywhere while Gold was the #3rd best-selling 3DS game with two days worth of sale and then 2nd for its first complete month.
If that helps contextualize WW Gold's performance, Famitsu currently has the game at 107k~; the Mario & Luigi superstar saga remake sold 71k in its entire lifetime according to the same tracker despite being released a year earlier in a completely dead week and a slightly less crappy market for the 3DS - and that's getting a sequel, so....