well u always see some very top team have roster wit salary of 1 mil in total or more than tat,they cant support the team for 1 season without experiencing losses so they tend to buy alot of players wit a lot of high salary at very low prices for important games like playoff or bbb games and then sell after tat.
for example:u see center wit 300k to 500k will go for lw prices bcoz most team cant support them,so top teams buy them and use them for short term and sell again
tis is basically player rent :)