Smart investing got millionaire investors where they are today in terms of wealth, but that doesn't mean millionaire investors enjoy the process of investing.

Spectrem's Millionaire Corner 2014 study Financial Attitudes and Concerns reveals that 83% of millionaire investors with a net worth between $1 million and $5 million believe that smart investing was a factor in their wealth creation. Only "hard work" (94%) and "education" (87%) exceed smart investing in terms of factors credited with creating wealth for millionaire investors.

However, when asked if they "enjoy investing and don't want to give it up," only 47% of millionaire investors agree or strongly agree with that statement. That compares with 58% of ultra-high net-worth investors with a net worth between $5 million and $25 million.

Sixty percent of millionaire investors say they are fairly knowledgeable about investing but still have a lot to learn, while only 19% consider themselves very knowledgeable. Twenty percent admit they are not very knowledgeable about financial products and investments.

The greatest regret millionaire investors have regarding their financial decisions before the recession of 2008 is that they did not take more risk in their investments. Twenty-five percent of millionaire investors said they wished they had taken more risk. On the other side of the risk spectrum, however, 24% said they wished they had saved more money before the event.

The only other regrets that received a significant number of nods from millionaire investors were "done more research about finances on my own" (16%) and "invested in more real estate or real estate products (15%).

It's revealing the attitude millionaire investors have about their own wealth status, namely in the question of whether they are wealthy. Asked to place themselves on a sliding scale from 0 (poor) to 100 (wealthy), the millionaire investors averaged themselves to 63.91. High-net-worth investors came in at 72.14.