Final answer:
The sentence that best supports the idea that artists must work hard to succeed is sentence number 2.
Step-by-step explanation:
The sentence that best supports the idea that Roubieu believes artists must work hard to succeed is sentence number 2: To be an artist you have to be so dedicated and it came to the point that it was so hard, I was contemplating quitting. This sentence highlights the dedication and hard work that Roubieu believes is necessary for artists to succeed.