#monero suffered a nearly successful 51% attack. While it didn't quite complete the attack, it came close, proving its vulnerability.

The reason a coin like XMR can be attacked is that there are few interested miners. This lack of interest stems from the coin's low price: there's barely any mining profit. Large groups of external miners can easily attack these low-value coins, not just Monero.

Those making this criticism miss an important point. When a system is attacked, you have to invest resources and money into the attack. When the cost of the attack is higher than the amount attacked, it's not done. In fact, many modern security systems are based on this principle, even national defenses: defenses are set up that make the cost of the attack so high that it's not worth it.

The conclusion is that it doesn't make sense to attack coins with low mining value, for that very reason: they're worthless. The ratio of mining cost to mining profit is very low. So no one will attack these coins.

The qubic.org group was the one who attacked Monero. But they didn't do it to profit from dominating the network. They did it to prove it was possible: that was their incentive; one that others won't have because it's already been proven.