Explanation of ethereum security

Could someone explain or direct me to a resource (have tried searching this group) that explains why ethereum's security is more important than other chains e.g. avax, matic, ftm, etc. and what the practical real world implications of this are?

Apart from liquidity incentives, I would like to know the reason for being on a particular chain i.e. which chain would you use once the incentives run out? I imagine that security would be the most likely reason to stick around on a chain?

From the most used chains here I cant figure it out https://defillama.com/chains

e.g. BNB and SOL are centralised but highly used; AVAX and FTM just have liquidity incentives...

In the top 10 would you say after ethereum that Terra is the most decentralised?

** Why would someone use MATIC over Arbitrum?

I have only used bsc, avax, ftm and matic and although rewards are lower on matic, this is my preferred chain.

Thanks!