Some people like the whole 'catalog the loot, ship it off for nuyen' process, so saying 'it takes RL time' is completely irrelevant at some tables. I've got a buddy at my table who loves to tally up the weapons and what is left of the armor after every fight and sell it along with whatever else he has the time to scrounge. His penny-pinching when it came to loot has eventually gotten him a barony, which got him titled as a general, which has put him in the top ten most powerful people in two countries.
Keep in mind if you take it straight to a Loyalty 4 contact who can deal with such goods (arms dealer, chop shop, jailbreaker, etc.) you automatically get 20% of the value and the problem is no longer on your hands. 20% of a 1,000 nuyen item is 200; that can purchase...
2 Lethal Grenades
2 Burner Commlinks
100 Rounds of Mundane Ammunition
1/10th of a Month of Low Lifestyle
An Acceptable Low-Level Bribe
A Good Number of Surveillance and Counter-Surveillance Items (think bug scanners, noise generators, jammers, etc.)
That's a lot of options for grabbing a single decent item (like an AK-97, an Armored Jacket, a Renraku Sensei Commlink, etc.). Spending a few minutes when possible to pick up some kit can pretty much cover your expenses for going on the 'run, which in turn means you have more money for advancement.
As BigGuns is saying, if all you're getting is 10K for a run, you're going to be light in the pockets. You automatically cut out a fifth of that for Lifestyle if you're Low, half for Middle, ALL of it for High Lifestyle. Getting new SINs will drain more over time, even if you're only going through a SIN every three jobs or so. A DocWagon (or comparable business) cuts even deeper. Medical expenses alone could break your bank. Assuming a 'run a month, replace an acceptable SIN every three months, lets go with Low Lifestyle, with Medium after the line...
120,000 Nuyen Earnings
-24,000 Low Lifestyle/60,000 Medium
-40,000 SINs
-5,000 Basic DocWagon
=51,000 Nuyen/25,000
Your profit before other expenses come into play is 42.5% if you're skimping on things, just over 20% for a moderate set-up. Twelve 'runs to get a bit over 50k in your pocket, if you're lucky and a cheapskate. That's not a whole lot, given you've put yourself in harm's way twelve times. Each 'run can take anywhere from what, 2-10 sessions of play to get through? 24 to 120 days of play to get that much money is abysmally slow.