The phrase 说到底 "in the final analysis"
The phrase 说到底 
is used to summarize or to conclude a previously stated idea.
is used to summarize or to conclude a previously stated idea. Pay attention
If the phrase is placed at the beginning of a sentence, we should put a comma after it.
If the phrase is placed in the middle of a sentence, we should put a comma before it.
Examples
他身体那么好，说到底是锻炼身体的结果，只吃不锻炼，身体肯定好不了
He's in good health. He exercises a lot, after all. If a person eats a lot and doesn't exercise, his health won't improve
tā shēntǐ nàme hǎo, shuō dàodǐ shì duànliàn shēntǐ de jiéguǒ, zhǐ chī bú duànliàn, shēntǐ kěndìng hǎobuliǎo
说到底，这是人品问题
In the end, it's all about someone’s character
shuō dàodǐ, zhè shì rénpǐn wèntí
那群家伙，说到底只是一群只为求财的毛贼而已
After all, these guys are just a bunch of thieves who only need money
nà qún jiāhuo, shuō dàodǐ zhǐshì yì qún zhǐ wèi qiúcái de máozéi éryǐ