Those seem incompatible to me.
(UBI means Universal Basic Income, giving everyone a basic income, for free)
If security is the enemy of capitalism, how do you explain people who have their needs met, who still strive under capitalism?
People who have their needs met would strive regardless of capitalism. You need to show that they strive because of capitalism. The problem is, capitalism doesn’t meet the needs of a large amount of people. No matter how hard they strive. Nor should it be necessary for them to. Worse capitalism short changes them. And is very inefficient.