Van Gogh’s early works were rather dark. Look up the Potato Eaters. His brother told him he needed to spice it up a bit in order to sell his work.
Van Gogh was a modern art collecter’s dream. He was in poor health, drank too much, suffered from mental illness, produced a couple of years of quality work, then shot himself to death.
He had very little professional success and died thinking himself a failure.
His life was certainly sad. The Dr Who episode about people who wanted his life to improve, but couldn’t help him had a grain to it. It’s very difficult to help someone with mental problems and, if he was awkward in interactions with people, it wouldn’t encourage people to help him. Incredibly sad. The scene of them letting him know that his work was beloved today was the most desperate wish fulfillment for people who loved his art.