I wouldn't use the word "irresponsible", but I think that 9 times out of 10, higher education is worth the investment, especially if you can afford it. Yes, there's always exceptions and there's a fair share of people who have become successful without a college education. However, for the grand majority of the population, I would definitely recommend a college education.
In terms of educating yourself, this is definitely do-able, especially in today's age of technology. It is becoming easier to teach yourself college courses though resources such as khanacademy and even YouTube. I believe MIT has offered a range of free college courses. While I would definitely encourage using these resources as a supplement to higher education, I would hesitate in stating that this can displace a college diploma, even if the quality of education is the same.
Ultimately, to get your foot in the door, you would have to present a resume. Frankly, to my knowledge, having a college degree on your resume, especially from a respectable university, looks much better than not having a college degree. You could learn the same exact material on your own without going to college, but in the end, it's the credentials that the college provides you with that helps you land that job. The money you spend on higher education gets you the education, but it's ultimately the diploma that you have to show for it. I hope this helps you out. Best of luck in making your decision.