This for me is a hard NO.
$6 in DEC is roughly 230 SPS
Land currently gives roughly 1.3 SPS a day
Splinterlands is asking for 177 Days out of 1,825 (9.6%!!!!) worth of your SPS rewards and if you don't pay then your rewards will effectively reduce (because others will inevitably pay)

If everyone who owns land buys the potions the average rewards remain the same. The only profit from this comes from those who either cant afford or are unwilling to pay.