when the discount rate is 0, the NPV is simply the sum of all payments in the series, so an infinite series of payments (e.g. rental income) is worth infinity
in reality, bad stuff happens: building burn down, renters leave, etc. so the right thing to do is to discount the payment stream by some risk function, particular far off payments
https://www.investopedia.com/terms/n/npv.asp
when the discount rate is 0, the NPV is simply the sum of all payments in the series, so an infinite series of payments (e.g. rental income) is worth infinity
in reality, bad stuff happens: building burn down, renters leave, etc. so the right thing to do is to discount the payment stream by some risk function, particular far off payments