Because the surface of Venus is so hot, we have sent very few probes a few decades ago, and they transmitted data for only a few minutes before dying. We have not been back since.
Maciej Cegłowski, in a partly gated article, offers a different perspective. He starts by pointing out how little we have invested in Venus compared to Mars by quoting NASA:
Humanity has accumulated 31 years of surface time on Mars and 49 years in Martian orbit, but we’ve spent just 4.5 days spent exploring the Venusian atmosphere, and 9.4 hours on the surface. When you consider that every mission to Mars has brought fundamental shifts in our understanding of the solar system, it would be strange if Venus didn’t have surprises waiting for us as well.
He makes the case for going by pointing out that while the surface is hellish, further up it may not be so bad after all:
The pressure and temperature in the high clouds are so Earthlike that, if not for the acid, an astronaut could sit in the gondola of a Venusian blimp wearing only an oxygen mask and a swimsuit.
Later, Cegłowski mentions that newer technology may make it possible to send probes that survive longer than the Soviet Venera landers in the 1980s by using heat-resistent components.
There may even be life in the atmosphere, even though it’d have to exist with very little water:
There are anomalies in the Venusian atmosphere that are consistent with the presence of life. Unlike on Mars, where any living microbes are presumably deep underground, life on Venus can only exist in the clouds and should be easy to observe (or rule out) with cheap balloons and aerostats […] Any life that existed there would have to fight for each molecule of water against sulfuric acid, which is desperately hygroscopic. While complex organic chemistry can exist in acid droplets, it would not resemble anything like the biochemistry we know on Earth.
Nehaveigur 