Of the practices of the righteous predecessors was reliance on Allah and then self reliance. If it was possible to accomplish something for themselves, they would not ask others for help. This is something we don’t see much of today. Not only do we have a knee-jerk instinct to ask others for a hand or a boost, sometimes we even feel entitled to it.
One important reason to practice self reliance is one avoids debts. If you have a habit of asking people for favors, in an important sense you owe those people. Even if there is no written contract there, there is still some sense in which something is owed. The Prophet (s) said: “Whoever does you a favor, then reciprocate, and if you cannot find anything with which to reciprocate, then pray for him until you think that you have reciprocated him.” [Abu Dawud] This is something that can cause doubt in a fastidious person because the question always remains, have I prayed enough to truly reciprocate? Yes, it may be enough to say jazakAllah khayr, but in some cases it may not be clear, so best to avoid asking the favor if at all possible and avoid the serious matter of unpaid debt, which is something that has major repercussions in the akhirah.
Also practically speaking, when someone does you a favor and you owe them, you can never be sure what they will ask in return. To avoid the possibility of them asking for something you cannot oblige, you avoid receiving the favor in the first place, even if they offer it without your asking. This is the path of prudence.
If we see how the Muslim community at large has conducted itself over the past century and more recently in terms of getting assistance from different groups, different international bodies, etc., we can see clearly how much trouble has resulted because of a distinct lack of self reliance.
The spiritual benefits of self reliance are also plentiful. By turning away from the means and facilitation of others (as much as one can manage, of course), one naturally becomes more in tune to the reality, which is one’s utter need for and reliance upon Allah, who is the only source of benefit. This awakening deepens tawakkul and ikhlas. It also helps put one’s nafs and (perceived) dependencies in their place.