Billionaire entrepreneur and Shark Tank host Mark Cuban made a surprise trip to Washington, D.C., on Monday to speak at National Small Business Week -- an annual event hosted by the Small Business Administration. And apparently, the crowd of older business owners couldn't be more different than the usual hoodie-wearing millennials he is used to addressing.  

"You know what I love about this room? It's all 29-year-olds," he joked. 

He acknowledged that a lot of people in the room probably started young, including himself--he started his first business at 12. "But we don't stay 12, we don't stay 18, we don't stay 25, we go on. And as entrepreneurs, we always find ourselves being challenged, because there is always a new kid on the block." 

Cuban said he was happy to talk to an audience of people who had experience under their belts--and who, thorough hard work and perseverance, had achieved a certain level of success. (The event honors small-business people from every state, most of whom have run long-established companies.) "Because you don't get to be where you are right now without grinding," he said, praising their toil to create a substantial business.  

"You don't get to be where you are without understanding that sales cure-all; that your businesses are built on actually selling something, actually making customers happy, actually having to look and make a profit--what a nice concept."

It is particularly refreshing to reward business people for their success in this day and age, Cuban said, when some D.C. [politicians] are questioning their importance--"screw, them." 

"The reality is, you are every single thing you are cracked up to be," he said, adding that small business owners represent the nation's past, present and future. 

Cuban's appearance wasn't part of the SBA's original week-long schedule, and was only announced a few hours before he arrived. While he reportedly left immediately after the event, he stuck around long enough to personally hand out awards to the business owners who were state winners. His speech was taped by the SBA, which is planning to post it to YouTube. 

Cuban ended his remarks with advice that he also gives to all of his Shark Tank companies, starting with the most critical: Understand the importance of customers. "You don't own this business, your customers own this business." 

You also have a responsibility to share with your community how rewarding it is to be an entrepreneur and a business person. "If we want our country to be great, we have to convey that to others around us," he said. 

"I'm glad I'm talking to a room of 29-year-olds," Cuban concluded, saying teenagers and young entrepreneurs need their knowledge. "The wisdom that you bring, the things that you do that define your success, are the true harbinger, the true values that make small businesses great." 

The key to a company with great customer service, he adds, "is like great sex. You do your job, ask them if they like it, and if they say yes--do it again."