By having a small daily dollar value (the column "PoW Produced (24h) in [1]). All but the top 15 coins sorted by that column have less than $10k emitted per day in block rewards, which limits the power that miners can spend on competing for it.
By having a small daily dollar value (the column "PoW Produced (24h) in [1]). All but the top 15 coins sorted by that column have less than $10k emitted per day in block rewards, which limits the power that miners can spend on competing for it.
That would mean all but the top 15 coins are exploitable for under $10k per day
But the value of a 51% attack is roughly proportional to marketcap, so while they are cheaper to attack, there's less incentive for the attack. The most (relatively) vulnerable coins are those where the daily dollar value is low relative to the market cap.