As someone older who played this out myself long ago and has seen many others do the same since: unless you were a big college star playing on the national stage, or had the talent to be one, "chasing the dream" after college is a fool's errand. If you aren't now or never have been ranked in the top 20 in the U.S. for your event, you probably have a better chance of winning the lottery than making an Olympic team.
I saw a lot of guys who were decent but not outstanding in college and thought they were going to make some big breakthrough to national or world class if only they devoted their lives to it, got with the right training group or coach, etc. The odds of that happening are somewhere between slim and none. Several of these guys missed out on getting a good career path started and ended up driving buses or working in shoe stores, which sucks when you're 50.
Contrary to what many believe, unless you were born with amazing genetics you aren't going to make an Olympic team just by hard work and dedication alone. My advice: focus on your education, go to grad school, spend a lot of effort getting a good job and run for pleasure and health, such as local road races and all-comer meets.