$500K Lumpsum. A 10 year US Treasure bond with a YTM 4.29%, will turn that $500K into $714,500 after 10 years. Taking the 5K per month will give you $600k over the 10 years. Even if you have no intention of investing the lumpsum, the lumpsum is $500k now at the present value of money, compared to $600k total from the $5K payments with the constant rise of inflation.
You could purchase a growth asset now, that will have more worth over those 10 years too. Like a rental property, that grows in value, while also giving you a somewhat steady extra source of income near immediately. While the $5000 payments will stop in 10 years. the payments from the rental can continue on long after that point with the added bonus possibility of the rental property growing in value long after that point.
"Time value of money is the concept that money today is worth more than money tomorrow. That is because money today can be used, invested, or grown. Therefore, $1 earned today is not the same as $1 earned one year from now because the money earned today can generate interest, unrealized gains, or unrealized losses."