It seems because they have no idea at all how Bitcoin will be in the future, not because they don't care, and actually it's not just Bitcoin because Dogecoin is one of the coins also widely used for gambling, and at that time gamblers would bet thousands of Dogecoin on a single wager, which compared to its current price would be worth thousands of dollars for one bet.
The future is not something that can be known precisely, even when trying to predict it, it may not be accurate. This is especially true in the case of Bitcoin, which was truly unexpected by many of its owners at the time.
It could be possible that those people who were gambling and considered whales at the time also had investments in Bitcoin. It’s not right to just assume they were wasting Bitcoin, what if they separated what was intended for investment and what was intended for gambling?
Either way, these people were a big reason for Bitcoin’s growing adoption. It’s very clear that in the past, aside from the dark web, gambling was one of the major uses for Bitcoin transactions.