Final answer:
The painter's fear is that the people who appreciate his artwork are destitute and artistic.
Step-by-step explanation:
In the context of the painter's statement, the phrase 'visitors are not only destitute but also artistic' suggests that the painter's fear is that the people who appreciate his artwork are impoverished, both economically and creatively. The painter might be expressing concern that his work is not reaching a wider audience who can fully understand and appreciate its artistic value.