It is not true that "there have been many, many, many more attempts at Mars than missions that actually got there", see:
Mars exploration splits into two eras, the cold war competition between the U.S. and Soviets - which the U.S. won hands-down, Yay Mariner! Yay Viking! - and the past couple of decades with the U.S. and other countries collaborating in various combinations.
During the cold war the U.S. had a track record of 8 successful missions versus 2 launch failures. During the recent couple of decades we've had 9 successes versus 3 diverse spacecraft failures. And many of those successes have been far beyond mission profiles. So the NASA Mars team is about 17 wins against 5 losses. This would be regarded as stunningly successful in any sport.
The Soviets in the early days had many launch failures that can't really be charged to the Mars missions themselves - and were about the reverse of the U.S. cold war ratio for those that did get to Mars. It was still a remarkable achievement for them to place any one of those missions in orbit.
There have also been about a half dozen non-NASA Mars missions during the past two decades. Two Russian missions unfortunately continued the trend of never leaving LEO. And now India is one-for-one. May they keep it up! Europe is one-for-two and Japan is zero-for-one. Talk about small number statistics, but that's 2 wins / 2 losses. Quite respectable. One hopes other nations join the fun.
In the aggregate this is a remarkable tally of successful missions considering Mars is never closer than 50 million kilometers or so. Anybody know the corresponding statistics for missions in LEO?