Why is the secondary inlet temperature in a Pressurized Water Reactor (PWR) so high?

I think your confusion is that a condenser does not cool to ambient temperature, it cools to saturated conditions. The water needs to be subcooled before it enters the pump, but it is still at relatively high temperature and pressure.

There is another loop that cools the condensor. This third loop is usually connected to a cooling tower, lake, or river. The exit of the third loop is ambient.

This is a very good question. I think other responses did not understand your question. I believe your question is how the inlet water to the steam generator is raised to such a high temperature, higher than the temperature of the water from the condenser that sends water to the steam generator. The answer is the secondary system has many stages of moisture separators and feedwater heaters to pre-heat the water before it enters the steam generator. This is to increase the thermal efficiency of the cycle. A good engineering text on thermodynamics, such as one by Sonntag and Van Wylen explain this.