If Europe wants to do this more power to them. I believe they could so could China in a simmilar time frame.
Human space exploration is a bigger risk and investment then say rovers and orbiters but the reason we would explore space is that hope of one day going there.
Some early history parallels
China in the early 1400's was more advanced then the other europeans in terms of naval exploration.
quoted from link
"After the beginning of 1433 China's beginnings as a naval power were suddenly stopped, never to resume again. One reason for this was their great cost, at a time when the Ming were paying for their campaigns against the Mongols and financing the building of Peking, the expeditions were criticized as expensive adventures. The court eunuchs that promoted the expeditions came under considerable opposition from their rivals, the scholar-officials -- so much so that Cheng Ho's accomplishments were practically suppressed from the historical record. Cheng Ho was an organizer, a commander, a diplomat, and an able courtier, but he was not a trader. No chartered companies, like the Virginia Company or the Hudson Bay Company, emerged to found colonies or establish overseas trade. Unlike its European counterparts, the Chinese state remained uninterested in the commercial and colonial possibilities overseas. This was partially due to the Ming government's major source of revenue coming from land tax and not from trade tax. Thus Ming China failed to become a maritime power. Through this default, the Eastern seas and eventually China's own coast would be dominated by a secession of non-Chinese seafaring peoples -- the Japanese, the Portuguese and Spanish, the Dutch, and finally the British and the Americans."
Obviously it wasn't exactly the same but to me it rings a bell.
If we just sit and do nothing, if America becomes stagnant and tilt our head not at the stars but at the ground, may we suffer the same fate. 16 billion a year is a small part of the federal budget and a small price to pay for space.
The specifics of how to explore are one thing rovers versus men. I think that rovers should play a part, but the whole reason we explore is to eventually pave the way for man. Human exploration is more expensive but the benefits are so much greater. A geologist or biologist on Mars could learn more than a 100 rovers.
Also the argument about them dying is void. No one is asking you to go. Once the landing site has been scouted you could find the people to go on a Mars mission. There would be hundreds of astronauts and scientist willing to take the risks and secure the trails for the rest of us. Exploration is inherently dangerous, but traveling into the unknown pushing the barriers always is and will be. But the risks are minimized as much as possible and we press on.
If you think that the problems in are country are because NASA is getting all this money you are wrong. Throwing NASA's budget at some social problem is going to aleviate the problem for a couple weeks at the most.