Self sabotage can often happen unconsciously. We may get unexplainable desires or make unwise actions for no apparent reason: that's our complex living inside of our shadow.
A complex is basically a repressed desire that caused us pain or trauma in the past, and that we're now neglecting. We pushed it away into our unconsciousness pretending, by doing so, to free ourselves from it. But not confronting it, we're letting it live inside of us without control: it can come out of the shadow whenever it wants and sabotage our desires and dreams whenever we seem to finally get over our deepest fears and change our life. That's because we unconsciously fear that our deepest needs won't be met: in that moment our complex comes out of the darkness and blocks us, by literally creating mental blockages or making us renounce to situations or procrastinate, so that we won't get hurt by unmet needs anymore.
For example: we're lacking money and we see money as a mean to get independence, but also as a way to free ourselves from the connections that we don't want to have anymore (i.e. we need to carpool to work, we have to share our house...). Our goal is to be financially independent, so to buy our own car and house, and isolate ourselves. We may even think we don't wanna deal with people anymore and go live in a forest. But this may actually hide our need to have real human connections: in fact, our complex may come out anytime we are given an offer for a rise or a promotion so that we give it up (we may be insecure about being able to afford that position); we may become famous online and suddenly stop posting; we may feel suddenly very tired and unable to work on any project or not plan properly our business. That's because our complex wants us to maintain those little connections we have on daily basis.
Our complex on one side wants to be acknowledged in our conscious self and be taken care of (it's still a human need/desire that caused us pain), so that's why it sabotages any chances you get to reach your goals. We may not understand why we say or do something sometimes, but our complex is doing its job keeping us where it wants us to stay. On the other hand, our complex wants to keep going unnoticed in order to keep doing what it wants to do and take control over us, kinda rebelling against us, destroying our dreams and keeping us where it's safe, exactly because we're neglecting it.
How to get over this matter? We need to be aware of what is going on in your conscious life by observing ourselves and being objective: whenever we make unreasonable excuses in order to not reach our goals, we should stop and think about the hidden reasons to find solutions that can help us mantain a balance among our complex's needs and our dreams. For example, to challenge our complex and make it lower its toll on us, we can start thinking that by being more financially independent, we may have more time to actually have a better social life (but ofc, we need to believe that and do that... our complex is still ourselves, not someone else: it knows when we're lying to us).