Question is...in general, what conditions cause the cells to self-destruct, eg. vent, explode, melt-down, etc.
The most prominent reason, by far, is poor cell-level design and/or manufacturing quality, from the lack of cell safety features (shutdown separator etc.), to outright manufacturing defects such as contaminants, electrode alignment problems...
Slight electrical abuse may increase the risk of catastrophic failure on high quality cells, too, but the risk is still very small, because it's miniscule to begin with.
For non-quality cells, I don't like speculating, because you never know. Some may go off without any abuse at all, some may be surprisingly good, until you buy more from another batch. This is why if you are concerned about safety
at all, you absolutely must buy Samsung, Panasonic, etc. Or take the very real risk.
Now, to the abuse side:
Thermal abuse is the worst. Thermal runaway onset temperature depends on the chemistry, but all modern high-capacity li-ion chemistries are at about 160 deg C. AFAIK, they can't lower this no matter what safety features they design in. This (about 150-170 degC) is the hard limit for any li-ion brand, if it uses LCO or NCA chemistry. Of course, real damage happens way before this limit. Competeting chemistries with higher onset temperatures (LMO and LFP) are unsatisfactory for other reasons. Thermal abuse point is really important, because if you
really fail your electronics side, it can heat up even the best quality, safe cell over it's onset temperature! Design proper fusing, and don't design in high-power resistors dissipating several watts for balancing.
Mechanical abuse; it depends. Low-quality cells have high chances of blowing up if you penetrate the cell with a nail or crush it. Higher quality cells are not immune, either, but the risk is smaller. 18650 is relatively safe due to the strong steel casing.
Overcharging; depends a lot. High-quality cells are unlikely to blow up even if you severely overcharge them (like connecting to 12V for hours!), but it can happen. Going to about 4.30V should be safe (while shortening the life), expect for the poorest cells that are on the brink of exploding anyway.
Too high charging current: Comparable to overcharging, but partially different mechanism. High-quality cells are unlikely to really blow up. Same thing for charging at temperatures too low.
Charging after severe overdischarge; again, depends. Severe overdischarge causes copper dissolution, and copper ions can build up dendrites which cause internal shorting, similar to lithium plating. Any cell below about 1.5V-2.0V should be discarded. High-quality cells are rather immune, because they are designed to be immune against internal shorts.
Having said all this, you should still avoid abusing even the highest quality cells. No cell is completely immune to abuse, there always are increased risks.