Norway had a per-capita GDP 10x that of Venezuela when they launched their fund. The option was a luxury that they were granted by already being a fairly wealthy country.

Also, consider if 25% of Norway's oil revenue is sufficient to provide a basic functioning government. Now you have Norway saving 75% of their oil revenue every year, and Venezuela still sucking 5% out of other funds, resulting in a long-term extremely wealthy Norway and a destitute Venezuela.