>>60612740 (OP)You don't. You need an army of ASIC processors to even have a chance of mining for profit.
>if there are only a finite amount in existenceThis IS the incentive, or at least part of it, because that's what stops inflation devaluing it to shit.
>confirm no transactionsThere will always be transactions. About 2,000 per block currently and this realistically won't go down.
>no rewardThe reward comes from the coinbase (new generated coins) AND transaction fees. There will always be the latter.
Even if this disincentivises mining a bit, it's always a really clever self-controlling loop, because if you get less reward, there's fewer miners, difficulty reduces, cost reduces, reward comes back up - it will always balance.