YALTA, Ukraine — One of the paradoxes of our age is that we are simultaneously living through a time of positive economic innovation and also a time of the painful erosion of the way of life of many middle-class families.

Listening to Yuri Milner, the Russian Internet investor, at a conference in Ukraine a few days ago brought home this contrast. Milner is a billionaire thanks to his Internet investments: He has done well both in his homeland, supporting some of Russia’s most successful start-ups, and, even more spectacularly by venturing abroad, taking pioneering stakes in Facebook, Zynga and Groupon.

When Milner talks about the technology revolution, he paints a dazzling picture of literally unprecedented innovation, bringing tremendous savings and benefits to consumers.

But when you talk to economists about the impact of those same forces on middle-class jobs, you come joltingly down to earth. The revolution Milner describes is part of a sea change in how the economies of Western industrialized nations work – and one that is hollowing out the middle class.

The technology revolution has become so familiar – grandmothers are on Facebook and toddlers navigate YouTube on their parents’ iPads - that it is easy to forget how revolutionary it still is. But Milner, speaking at an annual conference held by the Ukrainian billionaire Victor Pinchuk, argued that it had just begun to radically reshape our lives. (Disclosure: I moderated many of the sessions.)