If it says you have to wager a thousand dollar, it doesn't mean you have to spend and waste a thousand dollar.
You can wager this amount with only a buck in your balance if you are lucky enough and how much you are going to spend depends mainly on the game's house edge.
First of all, wagering is not only about losing or winning, it is the X amount of money that you wagered irrespective of whether you win or lose the bet. In both cases, wagering would be counted.
Also, wagering 1000$ with a single buck is not so easy and you need to be extremely lucky to achieve this. A more reasonable example would be that you may need 100 - 300$ to wager around 1000$.
Anyways I agree that the understanding of wagering is not much clear to the gamblers and they often miscalculate all this.
$100-300 is too much to wager $1000, if you need that much just to wager $1000 means that you have no idea how to wager effectively and with less risk. Lets just use the simple math of the house edge, if the house edge is 1%, you are supposedly to lose $10 to wager $1000. You will need hundreds buck to wager a thousand if you play high risk game or high risk strategy, if the main purpose is just to wager, we can simply bet low amount but make so many bets. It is more reasonable than you have to own 100-300, of course having 100-300 will make you wager faster but it is not wise to do if the main purpose is just to achieve such low wager amount.