The reason there are no massive planets in our solar system, comparable in size to gas giants like Jupiter or Saturn, closer to the Sun is primarily due to the processes involved in planetary formation and the characteristics of our solar system.
Planetary formation begins with the accumulation of dust and gas within a protoplanetary disk surrounding a young star. Closer to the star, where temperatures are higher, it becomes more difficult for gas to condense into solid particles. As a result, the materials available for planet formation in the inner regions of the protoplanetary disk are primarily rocky or metallic, while the outer regions have a greater abundance of volatile compounds and gases.
When a planet forms, it starts as a core of rock and metal. In the outer regions of the protoplanetary disk, where temperatures are cooler and more volatile materials are present, these cores can accrete large amounts of gas and become gas giants like Jupiter and Saturn.
In our solar system, the region closer to the Sun, known as the inner or terrestrial region, was not conducive to the formation of gas giants. The temperatures in this region were too high for significant amounts of gas to accumulate, leading to the formation of smaller, rocky planets like Earth, Mars, Venus, and Mercury. These planets are primarily composed of rock and metal.
It's important to note that our solar system is just one example among countless planetary systems in the universe. Other star systems may have different configurations and a wider range of planet sizes and compositions. In fact, many exoplanetary systems discovered outside our solar system have gas giants in various locations, including closer to their host stars.