Is a 401k even worth it? How much should I contribute to my 401k at 23, 24 or 25? How much should I contribute to my 401k at 30?
You may be thinking you can't afford to contribute anything to your 401k right now. But the money you put in now, tax-free, will grow for a very long time before you withdraw it at age 59.5 years old.
Therefore, I would recommend putting in at least some now, so it will grow and take advantage of compounding year after year.
With that said, a 401k is not worth it in all situations, and don't invest your money in something stupid: a 401k is just a tax-advantaged account "sponsored" by employers, it is NOT a specific investment.
Saying "I invest in my 401k" is like saying "I invest in my brokerage account." It means nothing.
Some folks can be making terrible 401k investments, in mutual funds they don't understand with very high expense fees, while other people may be making GREAT 401k investments in low-cost index funds or "stable value funds" -- taking advantage of whatever company match is offered, and assuring that their principal is not wiped out in any sort of sudden market downturn or unexpected volatility.
I would personally contribute to your 401k at least up to the company match, if one is offered. Ask your HR department for details on this. For example, your company might match your 401k contributions up to the first 5% of your salary. If this is the case, there is no reason not to take this FREE money.
Literally free money, so take it. Contribute up to the match. If you're worried about losing your money in the stock market, see if your 401k provider offers a more conservative bond fund or a "stable value fund." (While these funds CAN lose value, it is not as likely as with certain highly aggressive mutual funds.)
If you're young and don't yet make a lot of money, a Roth IRA is another excellent option to look into. I personally contribute up to the company match in my 401k, and then try to shovel as much as possible (you're allowed up to $5,000 per year) into my Roth IRA.
The Roth IRA is a retirement account that uses after-tax money, rather than pre-tax money as with your 401k at work. The Roth IRA is totally individualized, so you have a much wider range of investment options. Also, unlike a 401k, you can withdraw your CONTRIBUTIONS from a Roth IRA at any time, even before retirement age, penalty-free. You can not do this with a 401k plan. Note: You cannot withdraw your "earnings" from a Roth IRA at any time, without incurring penalties. So the money your contributions earn over time... that money has to stay in. But your original contributions can be withdrawn whenever you want.
So, to answer your original question, yes a 401k plan is worth it in many cases. You should contribute at least up to the maximum company match amount.
But a 401k plan is not worth it for all individuals. If you have credit card debt or student loans to tackle, especially if these loans are high-interest, it may be a better move to get yourself debt-free BEFORE investing considerable amounts into any retirement plans.
You have plenty of time to worry about retirement. The #1 priority should always be to remain (or become) debt-free, to save plenty of cash, and to live a frugal lifestyle so you always have more than enough money available to you... and so that money never becomes a headache or a deciding factor in your life.
It's your life. Don't live it worrying about credit card statements or student loans. And don't live it solely for the future, either, stashing money into a 401k that you won't see for another 30 years. You need to strike a healthy, comfortable balance between present enjoyment and future needs.