I believe that OP actually means that "No bet is a waste" in the context of gaining experience of one's wins and also one's losses.
In the example you put on the table, I agree that the sport-betting lacks of one of the factors that make it worth to partake in.
Someone would argue that, even if someone does not watch much of the tournament and yet managed to get a win, it would not be a loss at all
Also even if someone place a bet and lose, not a waste because the gambling site will gain the profit and it also means it is not a waste. But if talking about this in another direction that pertaining to winning and losing, losing is just a waste.
I would not say that spending on losing your bets provides some special experience, as many people think. It's just a waste of your money is all. And the thesis about experience - it just calms the player to some extent from anger because of the loss. But if we are talking about hundreds of bets, both winning and losing, then here, of course, the experience of the game is already being gained.
You can only increase your chance of winning by staying updated about teams and their activeness but it's still all about prediction which can be right or wrong.
Not only the team but also about the performance of a club, especially in the laste five matches or so.
A team can not continue to win, it would be surprising if it is even a club at the low position on a table that defeat the strongest club. It is just better not to use more than necessary to bet, any bet can go in another direction that we think.
And this, of course, is also the right one.
If a player loses more than he can afford (this is a classic thesis of all experienced players, which they follow!), then after all, then there will definitely be problems with the need to find money somewhere for later life. If we are talking about a person who supports a family, wife, children, and old parents, then the problem can be very serious. Because he spends the money necessary for the normal existence of other people. It turns out he just robs them.
Well, who in the family can like it or leave it indifferent?
And then there will inevitably be a scandal.
Well, who needs all this?