|mmm - I have to say that I have built/rebuilt assorted computers over the years - and never used any kind of ant-static straps etc...|
Possibly I've been (very) fortunate; but then so it would appear have all my various colleagues too - they have not used anti-static straps either...
And if they're not too outrageously expensive (often items like these are marked up some...) then go for one. If it allows you to feel a little more secure - no harm at all in using one.
If in doubt - use one!
Important item to be aware of...
When going inside "any" computer - fully remove "all" power sources; which in the case of a laptop means also removing the battery as well as the mains power cord.
Do not install/remove etc. anything physically - until you "know" all power has been disabled//removed.
On most/all modern laptops if the battery is still in place (and charged) even with the mains input removed... there are still active volts running around inside - even when the laptop its switched off on the laptop itself. So remove the battery if going inside.
On most/all modern computers even when switched off on the computer itself - again there are volts running around inside - if active mains is still applied. (This applies equally to laptops - with the battery removed - but with active mains still going in.)
Historical... Pre ATX boards (upto the late 90s) "off" usually meant it was OFF; the on/off switch/button was a mains-switch - at least for desktop systems... But then it all changed...