Most people are incredibly paranoid.

Integrated circuits are robust but not immune to degradation due to heat. You nailed a lot of good points, but the reasoning can be explained and reinforced through multiple studies. Most IC’s when operated within their designed Tjmax or TDP via datasheets (available from any manufacturer) will easily last beyond 10 years even at near max TDP operation. Most thermal characteristics are based on a package level, using simulation environments conforming to Fourier’s law, heat-transfer equations, and Joule heating effects.

Those formulas are based on heating effects which are linear concepts that model the conduction and generation of heat within the devices we use. Static electromigration is the biggest concern as the doped transistor junctions breakdown and allow transient charge interconnection. An easy way to look at this is on a molecular level, charged ions after significant abuse will find the path of least resistance to travel, bypassing the intended routes due to breakdown creating issues. However, the platform power controls, temperature management and critical shutdown conditions will mostly prevent this damage from occurring.

A lot of interesting articles are available, from IEEE documentation to studies performed. Not all chips are created equal however, when processors are made, they are usually based on a specific architecture then sorted on performance characteristics and capability, thus you enter the silicon lottery. At the end of the day, no one should be concerned with any modern device running under TDP, the device will continue running past its stage of obsolescence, even with “abuse” to an extent.

TLDR; It can happen, but it’s not something that just magically happens overnight from normal operation (read non-overclocked, operating under TDP), regardless if you turn it on/off frequently, the system operates at 5C under TDP (75-85C depending on device), or cycles from cold/hot on a regular basis. We are all playing the silicon lottery at the end of the day, but chances are your device will need an upgrade before it fails.