There is a difference between investing and gambling. The difference is you know the gold you spend will be returned to you. Buying low cost Exotic Leather, to craft Misthide Bracers for vendoring at a profit, this is an investment.
Buying one expensive item on the Black Market Auction House
, after researching The Undermine Journal
and discovering it may well sell for triple your price. This is a learning investment. You are spending gold to discover something. You’re gambling that you won’t get the gold back, but you’re willing to take the risk in order to “buy” learning for yourself.
Buying 100 White Tickbird Hatchlings at whatevever-is-currently-cheapest, because you saw a Twitch Streamer level one to 25, and earn a thousand gold. This is neither a learning opportunity, nor an investment. It’s a pure gamble.