The Social Security Administration (SSA) reports that 21% of married seniors and 44% of unmarried seniors get 90% or more of their income from the monthly benefits they receive. And 59% of current retirees consider Social Security a major retirement income source, according to the Employee Benefit Research Institute.

But as someone who's nowhere close to retirement, I'm not banking heavily on those benefits. Not at all. Here's why.

Pile of Social Security cards

IMAGE SOURCE: GETTY IMAGES.

1. I'm not sure what those benefits will amount to

Each year, the SSA issues workers an earnings statement that shows how much income they brought in and what their benefits will look like in the future. The younger you are, the harder it is for the SSA to get that estimate down pat, so the numbers I'm looking at today may be nowhere close to what my benefits actually amount to once I'm ready to collect them. If my earnings take a substantial hit in the next few decades, I'll wind up with less money than expected -- and that's not a risk I want to take. And since I can't get an accurate handle on what my benefits will amount to, I'd rather not factor a somewhat arbitrary number into my personal calculations.

2. All benefits could be slashed in the future

Though rumors abound that Social Security is on the verge of bankruptcy, that's not actually true. What is true, however, is that the program is facing a potential financial shortfall that could force it to slash benefits to the tune of 20% as early as 2035. Of course, that's just the most recent projection, which means benefits may be reduced sooner, or later, or at a higher percentage, or at a lower one. Or there may be no cuts at all. The problem? We just can't predict what'll happen, and so I'd rather not bank on benefits I may not even get to collect in full through no fault of my own.

3. Those benefits won't replace all that much of my income

Social Security generally replaces about 40% of the average earner's pre-retirement income. But that's not a lot in the grand scheme of retirement. Most seniors need about 70% to 80% of their former income to live comfortably, and assuming my finances shake out similarly, that means even without potential cuts, Social Security still won't come close to paying all of my senior expenses.

4. I want the pressure to save

If I'm not counting on Social Security to fund my retirement, you may be wondering where I expect my senior income to come from. And hopefully, the answer boils down to savings. Like many workers my age, I don't get a pension through work, but I do contribute to a retirement plan consistently, despite being a freelance writer whose income is extremely variable. In fact, one reason I've pretty much written off Social Security as a viable income source is that I want the pressure to save as much as I can. If I let myself fall back on those benefits, I'll be less motivated to aggressively fund my solo 401(k).

Let's be clear: There's nothing wrong with factoring Social Security into your retirement finances when planning for your golden years. But to play it safe, you may want to assume that those benefits won't do much for you down the line, and take savings matters into your own hands instead.

The good news is that if time is on your side, you can build a healthy level of savings without sacrificing a ton. Case in point: Socking away $300 a month over 40 years will leave you with almost $933,000 in savings, assuming you invest that money at an average annual 8% return, which is just below the stock market's average. And remember, there's no such thing as saving too much money for retirement, so even if Social Security comes through for you to a greater extent than expected, you can't go wrong by funding your nest egg to the best of your ability.